STROOTUKE OF THE MAMMALIAN GASTRIC GLANDS. 3 6 1

The Structure of the Mammalian GastricGlands.

ft. R. Benslcy, B.A., M.B.,Assistant Demonstrator in Biology, University of Toronto.

With Plate 29.

IN a preliminary notice, published in the • Proceedings ofthe Canadian Institute/ vol. i, Part I, I gave a brief accountof some new points in the structure of the gastric glands ofmammals, which appear to afford a solution of the question ofthe morphological significance of the pyloric glands.

The view of Heidenhain,1 Ebstein,3 and Griitzner,3 that thepyloric glands are simply peptic glands without border cells,and that the pyloric gland cells are identical with the chief orcentral cells of the fundus glands, is no longer tenable.

Heidenhain * himself noted that in the fresh condition thepyloric gland-cells are finely granular, whilst the chief cells ofthe fundus glands are coarsely granular.

Langley and Sewall6 observed the same feature, but con-sidered that the undoubted presence in the pyloric glands ofpepsin in small amount was sufficient evidence of their pepsi-nogenic character. They concluded, therefore, not that thepyloric gland-cells are different from the chief cells of the

1 'Arch. f. mik. Anat.,' Bd. vi.3 Ibid.3 ' PMger's Arcliiv,' Bde. vi and viii.4 Herrmann's 'Handbuoh d. Phvs.,' Bd. v.6 • Journal of Pbysiol./ vol. ii.

VOL. 41, PAET 8.—NEW SERIES. C 0

362 R. E. BBNSLEY.

fundus glands, but that " pepsia formation is not necessarilyconnected with the formation of coarse granules;" and further,that " the chief cells of the fundus are a highly differentiatedform of the pyloric gland-cells."

The introduction of new methods has made us acquaintedwith new points of difference between the two kinds of cells.

Schiefferdecker1 found that the pyloric gland cells of thepig and man stained intensely in dahlia, a property which isnot shared by the chief ceils of the fundus glands, or by theglands of the oesophagus and mouth. He found, moreover,that the pyloric glands of the cat and dog did not stain indahlia, a fact which is of importance as indicating a differencebetween the pyloric glands of different mammals, and further,that these glands differed anatomically from those of the pigand man.

Bonnet3 also has studied, by means of aniline dyes, thestaining reactions of the various cells of the stomach. Hefinds that the pyloric gland cells stain differently from thesurface epithelium and from the chief cells in methyl violet,Congo red, and acid fuchsin.

R. Krause3 has observed that the cells of the pyloric glands,in common with many mucous cells, stain inetachromaticallyin thionin.

On the other hand, the results of research by purely physio-logical methods seem to point to a functional relationshipbetween the pyloric gland cells and the chief cells. Of thehost of observers who have examined the pyloric mucous mem-brane of the dog for pepsin, few have failed to find it, and itspresence ill the secretion of the pylorus has been shown byKlemensiewicz* and Heidenhain,6 who established pyloricfistulse, and found abundant evidence of the presence of a

1 ' Nachricliten d. Gottingen Gesellscli.,' 1884, p. 303.3 'Berichte d. Oberhessisch. Gesellscli./ xxix, 1893.3 R. Krause, " Zur Histologie der Speicbeldrusen," ' ArcL. f. raik. Anat.,'

Bd. xlv.* ' Sitzungsber. d. k. Akad. d. Wisaensch..,' Bd. lxxi.' 'Pfliiger's Arcbiv,1 Bd. xviii.

STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 3 6 3

proteolytic ferment, in Heidenhain's case even after the lapseof five months.

In his recent exhaustive compilation of the literature ofthis subject, Oppell attempts to reconcile the conflicting re-sults of these two lines of research. He concludes that thepyloric gland cells are cells sui generis, differing both fromthe surface epithelium and from the chief cells, and engaged inthe secretion of pepsin holding gastric juice.

The present state of our knowledge does not permit of anycomparison between the pyloric glands and the other glandsof the stomach, nor is it possible to compare them with any ofthe gastric glands of lower Vertebrates.

Further, the researches of Edelmann3 have shown that thereexists in the cardiac region of the stomach of many mammalsa peculiar kind of gland, called by him the cardiac gland,differing both from the fundus glands and the pyloric glands,and concerning which we are even more in the dark.

The application of new methods to the study of the gastricglands has convinced me that the pyloric and cardiac glandsof various animals are closely allied to one another, and thatthe various kinds of cells one meets are but the results ofdifferentiation along divergent lines from a single primitivetype. The pyloric gland cells, furthermore, are in mostmammals closely allied to, and in the cat, dog, and rabbitidentical with, certain cells in the neck of the fundus gland,which, up to the present, have been regarded as ordinary chiefcells.

A convenient starting-point for the descriptions whichfollow is afforded by the gastric glands of the frog.

A fundus gland of this animal may be divided into threeportions; the duct or stomach pit, lined by mucus-secretingcylindrical cells similar to those of the surface; the neck,occupied by very large vesicular-looking cells, which, althoughdifferent from the surface cells, are also regarded as mucouscells, and the body of the gland, occupied by granular proto-

1 ' Lelirbuch der vergleickendeu mik. Anat.,1 1896.3 'Deutsoli, Zeitschr. f. Tliierinedizin,' Bd. xv.

364 E. B. BENSJJEY.

plasmic cells, which secrete both acid and pepsin. In sectionsstained in the muchsematein solution of Mayer, the muci-genous border of the cylindrical cells of the surface and thewhole of the large vesicular neck cells stain intensely, indi-cating beyond doubt that the latter are mucin-secreting cells.Langley * has shown that during digestion these cells exhibitthe usual secretion changes.

The pylovic glands of the frog are made up of only twokinds of cells, those of the body and those of the duct. Theformer bear so strong a resemblance to the large mucus-secreting neck cells of the fundus glands, that one cannotavoid the conclusion, with Partsch, that they are of the samenature. They, too, stain intensely in muchaematein.

It is generally admitted that the two main kinds of cell ofthe mammalian fundus gland are the result of the differentia-tion of the one kind found in the body of the gland of lowerVertebrates. The view advanced by Oppel,3 that the mucousneck cells of batrachian and reptilian glands correspond to thechief cells of the mammalian gland has been, however, theonly attempt to find in the glands of mammals a morphologicalequivalent for these peculiar cells.

My studies have enabled me to establish what has hithertobeen unsuspected, namely, that there exists in the fundusglands of many mammals cells which are morphologically andphysiologically equivalent to the mucous neck cells of thebatrachian gland, and that the same relationship exists betweenthese and the pyloric gland-cells as obtains in the Anura.

These cells in the neck of the gland have received littleattention from histologists owing to their small size, and totheir being overshadowed by the large and numerous bordercells of this region of the gland ; they are generally regardedas small pepsin-secreting chief cells.

The fact that they are different from the cells lower downin the gland has not, however, entirely escaped notice.Bizzozero 3 noticed in the dog that the chief cells of the neck

1 ' Phil. Trans. Roy. Soc.,' vol. clxxii.s ' Anat. Anzeig.,' Bd. xi.8 ' Aroli. f. mik. Anat.,' Bd. xlii.

STRUCTURE OP THE MAMMALIAN GASTRIC GLANDS. 365

of the gland have a more transparent protoplasm than those ofthe body of the gland, and a nucleus compressed against thebase of the cell. Similar features have also been noted for theglands of the badger and hedgehog by Oppel,1 who callsattention to the fact that in the hedgehog the neck cellscontain less protoplasm than the chief cells of the bottom ofthe gland, and that this stains less readily with hsematoxylin.Bizzozero suggests that these cells may be a transitional typebetween the cells of the gland duct and the fully developedchief cells of the deeper portions.

My attention was first attracted to these cells in the glandsof the greater curvature of the rabbit, in sections of which,stained in haematoxylin, the chief cells appear as comparativelylarge cubical cells with deeply staining protoplasm, whilst theneck cells are small pyramidal structures which stain butfeebly. The question naturally arose whether this differencewas due to a different functional condition of the cells, or tothe cells being essentially different, and I turned for a solutionof the question to a study of the distribution of zymogengranules in the gland.

The stomach of the rabbit did not lend itself very readily tothis investigation on account of the comparatively short neckthat the glands of this animal possess, and because I was notthen able to fix the granules in any but the lowest portions ofthe glands. I therefore resorted to a study of the glands ofthe cat and dog, in which the neck region is relatively long.I subsequently discovered that it was possible to fix perfectlythe granules in all parts of the glands of many mammalsby means of a modification of Poa's blood-fixing fluid, preparedby mixing equal parts of a saturated solution of mercuricchloride in 95 per cent, spirit, and a two to four per cent,aqueous solution of potassium bichromate. I was also fortunateenough to discover a means of staining in a distinctive fashionwith indulin these peculiar neck cells, and the use of thesemethods has enabled me to extend the facts discovered in thecat and dog to the rabbit and other mammals.

1 'Lehrbucli d. vergleicli. mik. Anat.,' 1896.

366 R. B. BENSLEY.

My methods are briefly as follows :—Small pieces of thegastric mucosa are snipped off with scissors, and droppedinto the sublimate bichromate mixtui'e, where they remainfrom one half to two hours, according to their thickness.They are then transferred to 70 per cent, alcohol, in whichthey remain twenty-four hours, or until all the free bichromateis extracted, then to 95 per cent, alcohol. Sections of 3—5micra are cut after embedding in paraffin -by the oil of ber-gamot method, fastened to the slide, and stained. The resultsobtained by this method of fixation were controlled by thestudy of pieces fixed in alcohol, in aqueous bichloride solutions,and in the osmic acid fixing fluids of Hermann and vom Rath.The staining methods employed will be indicated in connec-tion with the special descriptions.

I have chosen for special description in the present memoirthe gastric glands of the cat and dog, because these presentthe most highly differentiated form of the gastric gland, andbecause the relationship obtaining between the pyloric andfundus glands corresponds so closely to that found in thehighly specialised Anura.

A. The Gas t r ic Glands of the Cat.

The fundus glands are elongated tubular structures, openinginto shallow depressions of the surface lined by mucus-secretingcylindrical cells, and called the stomach pits or gland ducts.The glands consist of two kinds of epithelial cells, the centralor chief cells and the parietal or border cells, and are divisibleinto two portions, a narrower superficial part called the glandneck, in which the border cells are in excess, and a deeper,wider portion called the body of the gland, in which the chiefcells predominate.

That the difference between the body and neck of the glandis of a more profound nature than a mere difference in relativesize, or in the relative numbers of the constituent cells, maybe readily determined by the study of the fresh mucousmembrane in an indifferent fluid. If, in a freshly killed cat,

STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 367

a piece of mucous membrane be snipped off, and as thin asection as possible prepared with a razor moistened withaqueous humour, and mounted under a cover in a drop of thesame fluid, it may be observed, under a low power and smalldiaphragm, that the mucous membrane is divided into asuperficial transparent zone and a deeper more opaque zone

(fig- 1).Under a high power (Zeiss, apo. 2 mm. and 8 oc.) the

opacity of the deeper zone is seen to be due to the presenceof numerous large, coarse granules of zymogen. Thesegranules are entirely absent from the superficial zone, althoughmany minute fat globules may be seen in both kinds of cells.

The superficial granule-free zone includes not only the pits,but a large portion of the glands themselves; and it may beinferred that the chief cells of the neck of the gland do notcontain zymogen in the form of granules.

This peculiarity of the distribution of zymogen granules inthe mucosa did not escape the notice of Langley and Sewall,1

as their figure (14) of the neck of the gland of the cat clearlyindicates. They, however, attributed the absence of granulesfrom the neck of the gland to the comparatively infrequentoccurrence of chief cells here.

It will be seen from what follows that the absence of thegranules from the gland neck is rather to be ascribed to thefact that the chief cells are different from those of the bodyof the gland, and are engaged in the secretion of a quitedifferent product. In order that the differences between thetwo kinds of chief cells may be clearly defined, it will benecessary to describe accurately the ordinary chief cell of thebody of the gland.

In sections from the greater curvature of the stomach of acat that has fasted one to three days, the chief cells of thebody of the gland present the appearance indicated in fig. 2.They are pyramidal or wedge-shaped, and so appear cubical ortriangular, according to the direction in which they are cut.The contents of the cell exhibit an exceedingly regular network

1 ' Journal of Physiology,' vol. ii.

368 B. R. BENSLEY.

of large meshes, and in thick sections present a vacuolatedappearance. The protoplasmic strands which compose thisnetwork are very coarse, and stain readily in h£ematoxylin, afeature which is particularly noticeable at the thickened nodalpoints.

In sections stained in gentian violet or safranin the ap-pearance depends on the degree of success attained in fixingthe zymogen granules. If they are well preserved they stainintensely in these dyes, and the cell is then seen to be filledwith large deeply stained granules, between which may beseen running the trabeculse of the protoplasmic framework.If the fixation is less successful the granules are found tohave swollen up, so that the whole cell stains diffusely—afford-ing, however, unmistakable evidence of the presence ofzymogen.

The relation between the granules and the protoplasm maybe clearly seen in sections stained in the Biondi three-colourmixture, in which the granules stain a pale blue and the proto-plasm red. In sections thus stained each granule is found tocorrespond to a mesh of the protoplasmic network. This is,then, not a true network, but simply the optical expression ofthe fact that the zymogen granules occupy small cavities inthe cell, which are separated from one another by thin films ofthe protoplasm of the cell. In hardened cells there is usuallya clear space surrounding each zymogen granule, but it is tobe inferred that in the living resting cell the granule com-pletely fills the cavity in the protoplasm which it occupies.

In the base of the cell, even after a prolonged fast, theremay usually be seen a small quantity of protoplasm which, onaccount of the peculiar properties it presents, seems to merita more extended description than is usually accorded it.

Langley * observed that the protoplasmic zone of the activecell contains a substance which stains more readily with osmicacid than ordinary protoplasm, and which he inferred to beone of the earlier steps or mesostates in the formation of the

1 'Phil. Trans. Roy. Soc.,' vol. clxxii.

STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 369

zymogen. Griitzner1 also noted this peculiar staining withosrnic acid.

Some information as to the nature of the substance inquestion is afforded by the researches of Macallum,2 whodescribes the difference in staining properties exhibited by theresting and exhausting pancreatic cell, and explains the dif-ference as follows:—" The chromatin of the nucleus gives riseto a substance which we may call prozymogen, sometimesdissolved in the nuclear substance, sometimes collected inmasses (plasmosomata), and finally diffused into the cellprotoplasm, uniting with a constituent of the latter aszymogen." In a subsequent research into the distribution ofassimilated iron compounds in animal and vegetable cells,3 hefound, in the outer protoplasmic zone of the pancreatic andmany other gland cells, a firm organic compound of iron,which he regards as the prozymogen of his earlier investiga-tion. A similar view is taken by Mouret of the nature of thefibrillar chromophilous element in the outer zone of the pan-creatic cell, and the term " prezymogen " is applied by thisobserver to the substance in question.

I have made a series of experimental studies of the gastricand many other glands, with a view of determining the relationof this substance to the formation of zymogen granules, andalso its source in the cell. The results of these studies will becontributed in a separate paper, and I will content myself atpresent with a recital of the facts that are of importance fromthe stand-point of determining the morphological relationshipsof the cells.

The prozymogen is co-extensive with the protoplasm of thecell, and, even in cells which possess only a small outer zone,usually presents quite definite staining and structural charac-ters, which enable one to decide with ease as to its presence.The most favorable material for studying its characters is offered

1 'Pfluger's Arcbiv/ Bd. xx.* 'Trans. Canadian Institute,1 vol. i, part ii, 1891.3 ' Quart. Journ. Micr. Science,' vol. xxxviii, part ii, new series.* ' Journal de I'Anat. et de la Phjsiol.,' annee xxxi, 1895.

370 R. R. BENSLET.

by the glands of animals that have been in active digestion forten to twelve hours, and therefore exhibit a well-marked outerprotoplasmic zone (fig. 3). In sections from such glands,stained in freshly prepared Mayer's hseraalum, a pure nuclearstain is obtained in all the cells, with the exception of thechief cells of the body of the gland, the outer protoplasmiczone of which also stains blue. A more vigorous stain of thisportion of the cell may be obtained by the use of Ehrlich'sacid hsematoxylin, diluted for use with a 5 per cent, solutionof ammonia alum in water. The sections, after staining inthis fluid, are washed in tap water, then dehydrated and mountedby the usual methods. Staining in very dilute solutions ofmethylene blue, gentian violet, or safranin, followed byrapid dehydration in absolute alcohol, and clearing in benzole,also gives a very serviceable stain of the outer zone of thecell. In sections so stained the outer zone of the cellexhibits an obscurely fibrillated structure, which reminds onestrongly at first of the striated epithelial cells in the intra-lobular ducts of the salivary glands (fig. 3). On closer exami-nation it may" be seen that the fibrillation in the outer zone ofthe chief cell is not so regular, nor are the fibrillffi so distinctfrom one another as in the salivary ducts.

The strong affinity for nuclear stains exhibited by the outerprotoplasmic zone of the chief cell is due to the presence in itof a chromatin or firm organic compound of iron, the prozy-mogen of Macallum, as may be shown by the reactions for thepresence of iron. If a section of a piece of mucous membranethat has been hardened in absolute alcohol be treated withammonium hydrosulphide, or an acid solution of potassiumferrocyanide, no reaction occurs, indicating that no inorganiciron is present in the cell. If, however, the sections be firsttreated with a solution of pure sulphuric acid in alcohol, con-taining four volumes per cent, of the former, for a period ofthree to six hours at a temperature of 37° C, and then, afterthorough washing in fresh alcohol, transferred to ammoniumhydrosulphide or acid ferrocyanide solution, a strong reactionfor iron is obtained, not only in the chromatin of the nucleus,

STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 3 7 1

but also in the outer protoplasmic zone of the chief cells of thebody of the gland. The reaction in the protoplasm is aboutequal in intensity to that obtained in the oxyphile nucleolus.The best method of demonstrating the presence of prozymogenis by means of the hsematoxylin iron reaction, recently an-nounced by Macallum.1 In this method, after unmasking theiron by means of sulphuric acid alcohol, the sections are carefullyrinsed in alcohol to remove all the free acid, then transferred to0"5 per cent, solution of pure hEematoxylin in water, which turnsevery portion of the section containing iron a peculiar slate-bluecolour similar to that obtained in staining by the iron-alumhsematoxylin method of M. Heidenhain. This is a much moresensitive test than the ammonium hydrosulphide or ferro-cyanide reactions, and serves extremely well to exhibit the ironwhen present in only minute quantities in the protoplasm. Insections so treated the outer protoplasmic zone of the chiefcell shows a distinct blue colour, indicating that it containsa considerable amount of unmasked iron. A reaction is alsoobtained in the protoplasm of the portion of the cell occupiedby the granules of zymogen, although not equal in intensity tothat in the outer clear zone.

The presence of a large quantity of masked iron in the cellprotoplasm is a feature which serves to distinguish the chiefcells of the body of the fundus gland from all other glandularcells in the stomach. The protoplasm of the border cellsshows no reaction whatever when treated in the manner indi-cated above; and that of the pyloric gland cells, of the cylin-drical surface cells, and of the chief cells of the neck of thegland gives only a faint reaction for iron.

The prozymogen or cytoplasmic chromatin differs from thenuclear chromatin in some respects, as is shown by its relationto stains. In sections stained in gentian violet the prozy-mogen takes a reddish metachromatic stain, which contrastsvery well with the colder blue of the nucleus and zymogengranules (fig. 4). In Biondi solutions, which give a good basicnuclear stain, the prozymogen stains reddish—not, however, a

1 ' Journal of Physiology,' vol. xxii, 1897.

372 E. B. BENSLBY.

pure rubin stain. Furthermore, washing in alcohol after stain-ing in safranin will extract the safranin from the prozymogen,and, as Macallum2 pointed out, from the oxyphile nucleolus,long before it is extracted from the basophile chrotnatin of thenucleus. I have made use of this property in connection withthe hsematoxylin iron reaction to determine the distribution ofprozymogen in the glandular cells of the stomach. In workingwith the hsematoxylin method alone one is often in doubtwhether an apparent reaction is a real one, or simply theresult of a nucleus lying in an upper or lower plane of thesection, and out of focus, acting as a light filter. If, however,the section after treatment with the hsematoxylin be wellwashed and transferred to a dilute solution of safranin in 30per cent, alcohol, then extracted in alcohol until the safraninis nearly all removed, cleaned in benzole, and examined, it isfound that whilst the nuclear chromatin has taken on a red-dish-blue tinge from the safranin, the oxyphile nucleolus andthe prozymogen have retained a slaty-blue colour, which itis impossible to mistake even in thick sections (fig. 5).

The fibrillated appearance presented by the outer clear zoneof the chief cell is of adventitious origin, and not in itself ofimportance. A study of the mode of growth of the zoneshows that the first indication of an increase of protoplasmis a thickening of the trabeculse separating the granule-containing spaces in the outer ends of the cells. Then,as the granules disappear from the outer ends of the cells,this thickening becomes more apparent, and affects more par-ticularly those trabeculse which are arranged in a directionparallel to the long axis of the cell, so that these give inoptical section the impression of longitudinal bars or fibrillae.

The fine fibrillation which Eberth and Miiller,2 Mouret,3

and others figure in the pancreatic cell may be seen in thegastric chief cell, only in the small amount of unused proto-plasm which is Usually seen in the resting cell. This not

1 'Quart. Journ. Mic. Science,' vol. xxxviii, part ii,new series.3 ' Zeitschr. f. wissensch. Zool.,' Bd. liii, supplement.1 Op. cit.

STRUCTURE OF THIS MAMMALIAN GASTRIO GLANDS. 3 7 3

rarely presents peculiar sheaf-like and concentric formswhich are not unlike the figures published by Macallum,1

Mouret,2 and others, of the nebenkerne in the pancreatic cellsof Batrachia.

A coarse fibrillation, similar to that exhibited by the outerprotoplasmic zone of the chief cell, I have also observed inthe cells of the oesophageal glands of the frog, and in theserous glands of the gustatory region of the tongue of therabbit and dog, the nbrillse being strongly chromophile andiron-holding in each case. Solger3 has described in the serouscells of the human submaxillary gland, and Erik Miiller 4 inthe submaxillary glands of the guinea-pig, rod-shaped elements,placed vertically in the bases of the cells, which stain intenselyin hsematoxylin. It appears probable that these also are smallmasses of protoplasm which owe their affinity for hsematoxylinto the fact that they are strongly impregnated with prozymogen.

Between the coarse fibrils in the base of the cell may beseen small vacuoles containing fluid, and in the pepsin-secret-ing cells of the stomachs of Batrachia the outer zone appearsrather vacuolated than regularly fibrillated. In osmic acidspecimens minute fat droplets may usually be seen in the outerends of the cells, the border granules of Langley.

The nucleus of the chief cell of the body of the fundus glandis placed near the base of the cell in the resting condition.It is spherical or slightly oval in shape, frequently exhibitingslight irregularities of contour. A well-defined chromatinnetwork and one or two large oxyphile nucleoli may be madeout in all stages of secretion. The latter are always investedby a thin layer of basic chromatin, which frequently collectsin small masses at certain points on the periphery of thenucleolus, as has occasionally been observed in the nuclei ofnerve«cells.

It will be seen from the foregoing that there are two salient1 'Trans. Canadian Institute,' vol. i, part ii, 1891.1 Op. cit.• ' Anat. Anzeiger,' Bd. xi.* 'Arch. f. mik. Anat.,' Bd. xl?.

374 R. R. BENSLEY.

features in the structure of the chief cells of the body of thegland, namely, the presence of granules of zymogen in a por-tion of the cell of varying extent next the lumen, and thepresence in large amount in the protoplasm of the outer endof the cell, and in that between the granules, of a kind ofchromatin called prozymogen, which stains strongly withhsematoxylin and other nuclear stains, and gives, after treat-ment with sulphuric acid alcohol, a strong reaction for iron.Further, the outer protoplasmic prozymogen-impregnated zoneexhibits a coarse fibrillar structure, which is a quite frequentmorphological feature of the ferment-secreting cell.

I have not been able to make out any primary structure inthe protoplasm, that is any differentiation into a firmer frame-work and hyaline interstitial substance, although such mayexist and be masked in the ferment-secreting cell by the largeamount of deeply staining prozymogen present.

In the neck of the gland the chief cells are of smaller sizeand more pyramidal in shape, and are present to the numberof one to four between each pair of border cells.

It has already been indicated in the description of the freshgland that the neck of the gland is devoid of zymogen granules.This may be readily verified by the examination of sectionsprepared after fixation in the alcohol bichromate sublimatemixture, and stained in gentian violet. Such preparationsexhibit exactly the same division of the mucosa into two zonesas has been observed in the fresh material, due in this case,however, to the fact that the zymogeu granules with whichthe chief cells of the body of the glands are filled stainintensely in the dye, and thus give a deep stain to the body ofthe gland, whilst the cells of the neck of the gland which con-tain no granules have only their nuclei stained. Under thehigh power not a single granule may be found in the chiefcells of the neck of the gland.

This absence of granules is not due to imperfect fixation, asmight be inferred, for one may see at the junction of the neckand body-cells of both kinds, side by side, some containinggranules of zyraogen, perfectly preserved and staining readily,

STEUOTURE OF THE MAMMALIAN GASTRIC GLANDS. 3 7 5

and others entirely devoid of these. Moreover one canreadily distinguish the two kinds of cells from one another,even when, as occasionally happens, the fixation of the granuleshas been imperfect. In such cases the zymogen-holding cellstill stains strongly, although diffusely, in gentian violet, whilstin the neck cell only the nucleus stains.

In sections from the stomach of an animal that has beendigesting for several hours and stained in hsematoxylin, thedivision into two zones may again be observed. In this casethe extensive prozymogen-holding outer zone of the chief cellsof the body of the gland stains strongly, showing that thedistribution of the prozymogen corresponds to that of thezymogen. The protoplasm of the chief cells of the neck ofthe gland exhibits but little affinity for hsematoxylin, and it isonly by means of the haeinatoxylin-iron reaction that it ispossible to demonstrate the presence of any cytoplasmic chro-matin at all in these cells. In sections of alcohol-hardenedmaterial, treated with sulphuric acid alcohol for three to sixhours in the warm oven, ammonium hydrosulphide or acidferrocyanide produce a scarcely recognisable reaction in theprotoplasmic portions of the neck cells. If, however, thesections be treated with aqueous hsematoxylin, according tothe method already outlined, a slight blue colour is obtained,which, however, is not to be compared in intensity with thestrong reaction observed in the chief cells at the bottom ofthe gland. The protoplasm of the cells of the surface, and ofthe duct of the gland, gives a similar faint reaction for iron.

The chief cells of the neck of the gland, therefore, lack thetwo most important features of the chief cells of the body ofthe gland; they contain no granular zymogen, and they containprozymogen in such small amount that they are rather to becompared in this respect with the mucus-secreting cells of thesurface and gland duct. It might be urged that these areyoung or imperfectly differentiated zymogenic cells, which asyet secrete their ferment in such small amount that its ante-cedents do not appear in the form of granules in the cell. Itis not at present possible to determine whether or not these

376 R. it. B1SNSLEY.

cells do secrete small quantities of pepsin, but a study of thepositive characters of the cell reveals that they possess differentstaining characters from the chief cells lower down, and areengaged in a different kind of secretion.

I shall describe in the first place the cells from the upperportion of the gland neck (fig. 6, a). These are conical orpyramidal in shape, and wedged in between the large ovoidalborder cells of this portion of the gland in such a way that invertical sections their broad end is usually directed towardsthe lumen. In sections stained in hsematoxylin and eosin thecell is divided into two zones, an outer protoplasmic zonestaining readily in eosin, and an inner zone engaged in secre-tion which stains with difficulty. The outer zone consists oftwo elements, fine fibrillse which join one another to form anetwork, and a hyaline substance filling up the interstices ofthis network. The inner zone exhibits a structure similar tothat of the chief cells of the body of the gland, and for similarreasons the accumulation of droplets of secretion forces theprotoplasm to simulate the appearance of a reticulum, althoughthe bars which compose it are not nearly so thick nor soregularly arranged as in the chief cells lower down.

The secretion in the cells of the gland neck stains intenselyin Bordeaux R and indulin, and these dyes, particularly thelatter, have rendered me considerable service in determiningthe distribution of this kind of secretion in the stomach, andalso in studying the secretive processes in the cells containingit. I have found the most convenient method of applying thisdye to be in the form of Huberts blood-staining fluid, con-sisting of two grammes each of aurantia, eosin, and indulin,rubbed up in a mortar with thirty grammes of pure glycerine.This fluid is diluted with from 100 to 400 times its volume ofdistilled water before use, and allowed to act on the sectionstransferred to it from water for five to thirty minutes. Thesections are then washed in water, dehydrated, cleared inbenzole, and mounted. On examination it is found that thered blood-corpuscles are stained yellow, the nuclei of all cellsa faint hsematoxylin tint, the border cells and chief cells of

STRUCTURE OP THE MAMMALIAN GASTRIC GLANDS. 377

the body of the gland red, and the white fibres of connectivetissue blue. The protoplasm of the chief cells of the neck ofthe gland also stains red, but the portion of these cells con-taining secretion stains intensely blue (fig. 6). Staining inindulin solutions alone does not give successful results, as thestain in this form is also taken up diffusely by the other cells;but mixtures containing only eosin and indulin, or orange Gand indulin, give fairly good results. This colour reaction isvery little affected by the mode of fixation, as it may beobtained in exactly the same features as indicated in fig. 6, inpreparations hardened in absolute or dilute alcohol, or aqueouscorrosive sublimate.

In sections stained in the indulin mixture the inner zone ofthe cell appears vacuolated, exhibiting in optical section anetwork of thick bars separating spaces, in which lies blue-stained secretion. The network also stains, as a rule, muchmore intensely than the secretion, indicating that it too isimpregnated with the indulinophilous substance. Not rarelyone may notice irregular clumps or flakes of deeply stainedsubstance lying in the spaces of the cell network, giving thecell a coarsely granular appearance. This is never observed incells fixed in aqueous sublimate, and is probably due to therapid extraction of water by the alcoholic fixative, and aconsequent precipitation in this form of the solids of thesecretion.

It will be noted that the inner zone of these cells, whenstained in the induliu mixture, exhibits a coarse network, whilein haematoxyliu eosin sectious the network is finer than in thechief cells of the body of the gland. The reason appears tobe that the solids of the secretion are precipitated along thebars of the protoplasmic network, and when intensely stainedgive these a triple thickness. In sections stained in concen-trated solutions of the indulin mixture, one sometimes findsthe true protoplasmic portion of the network stained red, andit then presents the same characters as in the hsematoxylineosin sections.

As one follows the neck of the gland downwards, it is seenVOL. 4 1 , PART 3 . NEW SKB1ES. DD

378 E. B. BENSLEY.

that (fig. 6, b) the portion of the cell engaged in secretionbecomes relatively greater, and at the lowest portion of theneck of the resting gland two zones are no longer to berecognised in the cell, the whole of which is concerned in theformation of the indulinophilous secretion. These cells of thelower portion of the neck of the gland are in structure exactlylike the cells of the mucous salivary glands in the secretion-filled phase.

Following the gland in the direction of the free surface, itis found that the cells of the uppermost portion of the neck,and of a varying portion of the duct or stomach pit, are alsoengaged in the formation of the indulinophilous secretion, theportion of the cell thus engaged becoming relatively less, andthe protoplasmic portion greater as one approaches the surface.The cells also, as the border cells become fewer, assume thecylindrical shape and become longer. In these cells (fig. 6, e)the secretion is found, for the most part, as a spherical mass inthe middle of the protoplasm of the cell near the nucleus.There is always, however, a small amount of indulinophiloussubstance diffused through the protoplasm intervening betweenthis and the free surface of the cell, and along the free surface.Passing up the duct of the gland this mass gradually approachesthe free border of the cell again, and becomes less stainableiu indulin, thus passing by a gradual transition into the rauci-genous border of the surface cylindrical cells, which in the catstains but faintly in the indulin mixture.

A further difference between the cells of the gland neckand those of the free surface is that the protoplasm in thelatter cells is of a denser character than that in the cells ofthe gland neck,—that is, it contains a larger proportion ofthe fibrillar element, and a smaller amount of interfibrillarsubstance.

Thus, although the cells of the gland neck differ from thoseof the free surface, both in general appearance and in stainingproperties, it is impossible to discover at any point interven-ing between the lowest part of the gland neck and the freesurface an abrupt change in the character of the cells. This

STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 379

in itself would suggest a similarity in the nature of thesecretion products of the cells, as well as a similarity in theirmode of origin. There are, however, additional reasons forregarding the secretion of the neck cells as of a mucousnature. Staining in thionin gives a faint metachromatic redstain to the secretion inside the cell, and in Mayer's muchse-matein the secretion of these cells stains even more intenselythan that of the surface epithelium. I may add that in thelatter fluid the chief cells of the body of the gland stain notat all.

The nuclei of these cells vary in shape with the amount ofsecretion present. In those cells which have a well-definedouter protoplasmic zone it is round or oval, and of regularcontour. In the cells that are filled with secretion the nucleuspresents the irregular, compressed, sometimes crescentic out-line usually observed in mucus-secreting cells.

Mitfltic divisions are, as Bizzozero l pointed out, most abun-dant in the cells of the bottom of the duct and of the upperportion of the gland neck, but they are by no means infre-quent in the chief cells of the gland neck themselves, andI have frequently observed cells completely filled up withsecretion with their nuclei in the various phases of indirectdivision.

The nature of the difference between the mucus secreted bythe cells of the gland neck and of the surface epithelium is apoint of some interest, but one which it is very difficult todetermine. The fact that the cells in which mitoses are mostfrequent contain secretion which stains with indulin, and thatthe cell$ of the gland neck containing a similar secretion alsodivide frequently, while the cells of the surface rarely undergodivision, would suggest that the difference is partly of thenature which Bizzozero3 has found to exist between thesecretions of the young and old mucus-secreting cells of theLieberkuhnian glands of the intestine. This is not, however,a sufficient explanation, as similar differences in staining re-

1 ' Arch. f. mik. Anat.,' Bd. xlii.a Ibid., Bd. xl.

380 R. E. BENSLET.

actions are found in cells which are strictly comparable mor-phologically. For example, the mucous border of the surfaceepithelium of the stomach of the rabbit stains iu iudulin almostas readily as the neck cells of the gland of the cat, aud in theintermediary zone of the rabbit's stomach there are peculiartransparent glands, the cells of which have all the features ofa mucous cell, but which stain differently from the cells ofthe neck of the fundus gland, from the pyloric gland cells, andfrom the surface epithelium. The only fluid which stains thesecretion of these cells is the muchsematein solution of Mayer,in which it becomes intensely blue.

The indulinophilous mucus-secreting cells do not ceaseabruptly at the lower end of the gland neck, but a few maybe found among the ferment-secreting cells of the upper por-tion of the body of the gland, as indicated iu fig. 6, d, andrarely one finds them even in the lowest parts of the gland.These cells in lisematoxyliu and eosin stained sections stainred, contrasting strongly with the more blue stained ferment-forming cells. It seems to me very probable that these arethe cells observed by Pilliet,1 Trinkler,2 and others, aud re-garded as stages in the transformation of chief cells intoborder cells, or vice versa,.

The cells of the neck of the gland exhibit the usual secre-tion changes. Iu the first hours of digestion very little changeis to be noticed; but after twelve hours of secretion, and moreparticularly when the stomach is mechanically stimulated bysponge feeding, the secretion is seen to have been largelypassed out into the lumen of the gland, where it stains readilywith indulin and rnuchseinatein, and exhibits the stringy orspongy texture usually presented by mucus outside the cell.At the same time the cell becomes reduced in size, and containsrelatively more protoplasm. Secretion changes may also beobserved in the cells of the bottom of the gland duct, therounded mass of mucus moving forward to the free surfaceof the cell, where it is partly discharged.

1 'Journal de 1'Anafc.,' &c, 1S87.2 ' Arch. f. mik. Anat.,' Bd. xxiv.

STRUCTURE OJF THE MAMMALIAN GASTRIC GLANDS. 3 8 1

It has seemed to me that there is an increase of indulino-philous cells in the body of the gland during the first hours ofdigestion, but I have not yet given this matter enough atten-tion to enable me to speak with certainty concerning it.

The discovery of the different nature of the cells of theneck of the gland affords a cytological basis for the division ofthe gland into two regions, a neck and body.

The neck of the gland, as determined by the distribution ofthe indulinophilous cells, varies in length in the different por-tions of the stomach. It is shortest in the glands of thegreater curvature, where it forms about one third of the gland,and longest in the lesser curvature, where it may comprise asmuch as four-fifths of the entire gland.

B. The Pyloric Glands of the Cat.These glands are, as Toldt1 pointed out, branched tubular

glands, consisting of a deep pit or duct lined by a continua-tion of the surface epithelium, and, opening into this, branchedtubules of various lengths exhibiting a tortuous course in thedeeper layers of the mucosa.

Disregarding the anatomical divisions of the gland, one maydivide it, on a basis of the nature of the cells, into threeregions : a funnel-shaped duct, lined by a continuation of thesurface epithelium (fig. 7, a); the tubular body of the gland,lined by the true pyloric gland cells (fig. 7, c) ; and a short por-tion connecting these, and lined by cells of an intermediatetype (fig. 7, b).

The true pyloric gland cells are, except as regards shape,identical with the chief cells of the neck of the fundus gland.They present all the characteristic staining properties of thelatter, and, if one compares similar secretion phases, are ofthe same structure. They contain a secretion which stains in-tensely in Bordeaux R, in indulin and Mayer's muchaematein,and, as R. Krause has already pointed out, gives a meta-chromatic red stain in thionin. This secretion I regard, forsimilar reasons, as of a mucous nature.

1 ' SiLzungsber. d. k. Akad. d. Wissenscli., VVien,' 18S1.

382 ft. B. BBNSLKY.

The cells of the pyloric glands contain neither in the freshcondition nor in the hardened and stained gland granulesof zymogen. Furthermore, the protoplasm of these cells isnot chromophilous to nuclear dyes, and examination for maskediron by the methods already indicated reveals but a trace ofprozymogen. The cells of the transitional portion of thegland resemble most closely those of the surface, but containa relatively larger amount of protoplasm. By means of Mayer'smuchpematein it may be shown that these cells always containa small mass of mucus at their free ends, but this is so smallthat, when using less decisive staining methods, it is readilyoverlooked, and the cell regarded as entirely protoplasmic. Inthese cells mitoses are fairly numerous, although they alsooccur in all parts of the gland proper.

These pyloric glands present exactly the same features asthe neck and duct of the fundus gland,—that is, althoughthe true pyloric gland cells differ both in general appear-ance and in structure from the cells of the surface, inpassing from one to the other along the gland at no pointcan one discover an abrupt change from one type of cell tothe other.

The secretion phases in the pyloric glands of the cat arepeculiar, and are represented in figs. 8—10. Fig. 8 showsthe condition of the gland after a fast of twenty-four hours'duration. The cells are comparatively long, with a spherical oroval nucleus placed near the base of the cell. The stored-upsecretion is found, for the most part, in the form of a narrowzone along the lumen of the gland, although it is not uncommon -to find a second mass of secretion in the deeper portion of thecell near the nucleus (fig. 8, a). It is also quite common tofind this second mass of secretion more stainable in indulinthan that along the free border, the cell then presenting anappearance closely resembling that already described for thecells of the lowest portions of the duct of the fundus glands.Sometimes, as in the neck of the fundus glands, the mucin isprecipitated in the form of irregular flakes or granules. A pro-longation of the fasting period even to four days does not

STRUCTURE OP THE MAMMALIAN GASTRIC GLANDS. 3 8 3

result in an increase of the amount of secretion stored up inthe cell.

Fig. 9 shows a similar gland from the pylorus of an animalkilled six hours after a copious meal of meat. The cells areincreased in length, and the nuclei exhibit a tendency to becomeirregular in outline and flattened in a direction at right anglesto the long axis of the cell. The portion of the cell betweenthe nucleus and the lumen is now entirely filled up with acoarse meshwork, which stains strongly in indulin, and containsa similarly staining secretion, although in many cells a divisionof this into two masses, partly separated from one another bya band of protoplasm, is still obvious.

Fig. 10 is from an animal killed twelve hours after a mealconsisting of several pieces of sponge soaked in beef juice. Thelumen of the gland is now increased in size, and the cells muchshorter than in the preceding phase. The nuclei have regainedtheir spherical shape, and are situated nearer the middle of thecell. The secretion has been nearly all cast out of the cell, sothat only an extremely small amount on the free border is nowto be recognised.

The pyloric glands of the cat illustrate in a very strikingmanner the fact that in gland cells the period of greatestloading does not always coincide with the end of a normalperiod of rest. Here it appears that the growth that takesplace in the cell during the rest period following the comple-tion of digestion results merely in an increase of the proto-plasm of the cell, and that during the first hours of digestion alarge portion of this is rapidly transformed into mucigen, sothat the real period of greatest loading is reached some hoursafter digestion begins.

Further evidence in support of the view that the indulino-philous cells of the neck of the fundus glands and the pyloricgland cells of the cat are identical is afforded by an examina-tion of the short intermediary zone. The first change thatone notices in passing from the greater curvature in thedirection of the pylorus is an increase of the indulinophilouscells in the body of the gland. At the same time the neck of

384 R. E. BENSL15T.

the gland increases in length. As the pylorus is approachedthese cells gradually replace entirely the zymogen-formingchief cell, and the proximal portion of the pyloric region isoccupied by short glands, consisting of indulinophilous cellsand a few border cells. Ultimately the latter also disappear,and we have the true pyloric gland.

C. The Gastr ic Glands of the Dog.A section of the fresh mucosa of the greater curvature of

the stomach of the dog, examined in aqueous humour, revealsmuch the same features as a similar preparation of the cat'sstomach. The superficial portion of the mucosa, includingnot only the pits but a large portion of the glands themselves,is entirely free from the zymogen granules that crowd thelower portion of the gland. The granules are smaller than inthe cat, and much more difficult to preserve, so that I havebeen compelled to rely on the examination of the fresh glandsfor control of my results.

In sections hardened in corrosive sublimate, or in thebichromate sublimate mixture, the chief cells exhibit the samestructural features as those of the cat, namely, a regular mesh-work separating spaces, which one may infer to have beenoccupied in the fresh cell by the zymogen granules (fig. 11),and in glands from a digesting stomach (fig. 12) of an outerprotoplasmic zone, which stains intensely and readily inhsematoxylin, exhibits a coarse fibrillar structure, and gives,after treatment with sulphuric acid alcohol for three or fourhours at a temperature of 37° C , a well-marked reaction foriron. In short, the cell contains both zymogen and prozy-mogen in large amount.

The chief cells of the neck of the gland, on the other hand,contain no granular zymogen, and only a trace of prozymogen.These cells are of the same nature as in the cat, and presentan inner secretion zone of variable extent, which stains intenselyin indulin and muchsematein. As in the cat, also, a gradualchange in the character of the cells is seen as the surface ofthe mucosa is approached.

STRUCTURE OP THE MAMMALIAN GASTRIC GLANDS. 385

It is an interesting fact that among the other cells of theneck of the fundus gland of the dog, cells may be found whichare in every respect similar to the cells of Stohr of the pyloricglands, as described by Hamburger.1 These are characterisedby their fusiform shape and their faintly staining protoplasm,in which wavy fibrillse may be seen. The pointed end of thecell which reaches the lumen stains intensely red both in theBiondi mixture and in eosin.

A point of some physiological interest is the varying lengthof the gland neck in the stomachs of different dogs. It will beseen from the following measurements that the differences inthe thickness of the mucous membrane are mainly due tovariations in the length of the body of the gland :

No. 1.. 2„ 8„ *.. 5

Thickuessof

mucosu.•68 mm.

. -608 „• -68 „. 1118 „. 1-387 „

Lengthof gliind

neck.. -28 mm.• "276 „

• 3

. -358 „. -37 „

Lengthof body

of gland.•4 mm.

. -332 „• "38 „• '76 „. 1-017 „

Percentage of

in zymogencsis58-854-655-8C7-973-3

<. T h e above measurements are taken from vertical sectionsfrom the middle of the greater curvature , stained in theindulin mixture , so tha t the junct ion of the body and neck ofthe gland was sharply indicated by the cessation of t heindulinophilous cells. I t is obvious t h a t such differences inthe percentage of the whole gland engaged in ferment secretionmust be taken into consideration in estimating the relativeamounts of pepsin in the mucous membrane in differentperiods of digestion.

The pyloric glands of the dog are in all essential featuressimilar to those of the cat, the main difference being that theducts are much longer and rather cylindrical than funnel-shaped, and the gland cells are much longer. The pyloric glandcells contain a secretion which stains intensely in BordeauxR, in indulin, and in mucheematein, and are in every respectsimilar to the chief cells of the neck of the fundus gland.

1 'Arch, f. mik. Anat.,' Bd. xxxiv.

386 R. B. BENSLBY.

The secretion phases are represented in figs. 13 and 14.The resting cell (fig. 13) contains already a great deal ofreserve secretion, the nucleus being crescentic and compressedagainst the base of the cell. In the exhausted phase (fig. 14)the secretion is for the most part confined to the free borderof the cell, although many of the cells exhibit spherical massesin the neighbourhood of the now spherical nucleus. Theprotoplasm is also very much increased in amount.

All observers are agreed that the fresh pyloric glands of thedog do not contain coarse granules. The only granules thatmay be observed are small globules of fat, which areparticularly numerous in the bases of the cells. The mucoussecretion of the cell, too, occasionally, as in the cat, precipitatesin a granular or flaky form, although I have never observedthis in secretions hardened in aqueous sublimate solutions.The protoplasm of the cell contains only a trace of prozymogen.

Co nclusions.In the cat and dog the fundus glands contain two kinds of

chief cells, those of the body and those of the neck of thegland. The former are engaged in the secretion of ferment,and are characterised by the possession of a large number ofzymogen granules which occupy a portion of the cell of varyingextent near the lumen, and a protoplasmic outer zone ofvarious size which stains intensely in nuclear dyes such asligeraatoxylin, and presents a coarse fibrillar structure. Thestaining properties of this outer protoplasmic zone are due tothe presence in it of a kind of chromatin, which may stand ina genetic relation to zymogen, and which has been named pro-zymogen.

I regard the cells of the neck of the gland, and the pyloricgland cells in the cat and dog, to be of the same nature, forthe following reasons :

The chief cells of the neck of the fundus gland and the pyloricgland cells do not contain at any period of digestion zymogenin the form of granules, and prozymogen is present only intraces.

STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 387

Both groups of cells are engaged in forming and secreting asubstance which stains intensely in Bordeaux Tt, in indulin, andin Mayer's specific mucin stain muchfemateiu, and which givesthe usual metachromatic mucin stain with thionin.

Both may be traced through a gradual transition to thecylindrical cells of the surface.

The assertion that the secretion of these cells is mucin restsas yet on the evidence afforded by the structure of the cell,and its staining in thionin and Mayer's muchsematein. Nomethod has suggested itself to me for securing the secretion ofthese cells unmixed with that of the surface epithelium, andtesting it for mucin. It is, however, on evidence of the samecharacter that the large transparent neck cells of the batra-chian gland have been accepted as mucus-secreting cells.

The chief cells of the neck of the fundus glands, and thepyloric glaud cells of the cat and dog, are the physiological andmorphological homologues of the mucous neck cells and pyloricgland cells of the frog, with which they correspond in situation,structure, functional changes, and staining. It is interestingto note that these cells in the frog and other Batrachia stainintensely in indulin when treated with mixtures of eosin,indulin, and aurautia.

The cells of the lowest portion of the gland duct or pit areof a type intermediate between the surface epithelium and themucin-secreting neck cells or pyloric gland cells, and formthe fundamental type to which the origin of both must betraced. Moreover the researches of Bizzozero1 have made itextremely probable that these, although themselves secretingcells, are constantly dividing, and so form the young elementsfrom which both the cells of the surface and the neck cells, orthe pyloric gland cells, are recruited, although it must beadmitted that the two latter are partially replaced by divisionamong themselves.

Mucin-secreting neck cells are present in the fundus glandsof the mink, rabbit, mouse, rat, squirrel, ground hog (Arctomys),chipmonk (Tamias s t r ia ta) , pig, and sheep. The relation

1 ' Arcli. f. mik. Anat.,' Bd. xlii.

388 B. B. BENSLEV.

existing between these and tlie pyloric gland cells on the onehand, and the cardiac glands on the other, will be discussed ina second paper now in course of preparation.

EXPLANATION OF PLATE 29,

Illustrating Mr. R. R. Bensley's paper on "The Structure ofthe Mammalian Gastric Glands."

NOTE.—All figures are drawn with the aid of the camera lucida, and, withthe exception of figs. 1 and 7, as seen under the Zeiss apnchromatic objective(2 mm. apert.) and compensation ocular 8. In fin. 7 the same objective andcompensation ocular 4 were employed. Figs. 2, 3, 11, and 12 are reproducedfrom grey pencil drawings, and do not indicate (.he colours of the originalpreparations.

F I G . 1.—A photomicrograph of a fresh unstained section of the niucosa ofthe greater curvature of the stomach of the cat.

F I G . 2.—Transverse sections of the lower ends of three fundus glands of

the cat after a fast of twenty-four hours' duration ; hssmatoxylin and eosin.

F I G . 3.—Transverse sections of the lower ends of three fundus glands ofa digesting cat, stained in hxniatoxyliu and eosin. a. Indulinophilous mucin-secreting cells. All othe;1 chief cells show a deeply staining outer zone withcoarse fibrillar structure.

FIG. 4.—Fundus gland from a digesting cat, stained in gentian violet. Theouter prozymogen-holding zone stains metacliromatically.

FIG. 5.—Fundus gland of cat fixed in alcohol. Section treated with sul-phuric acid alcohol, then with aqueous bsematoxylin, and finally stained faintlyin safranin. The prozymogen-holding outer zone gives a strong reaction foriron, which has been unmasked by the action of the acid alcohol.

F I G . fi.—Vertical section of the duct, neck, and upper portion of the bodyof a fundus gland of a fasting cat ; indulin, eosin, and aurantia. a, 6. Mucin-secreting chief cells of the neck. d. Ferment-secreting chief cells of thebody of the gland, f. Mucin-secretin™ cell of the body of the gland.

F I G . 7.—Pyloric gland of cat after a fast of twenty-four hours' duration ;indulin and eosin. a. Duct. b. Intermediate portion, c. Body of gland.Exhibits the gradual transition in passing front the body of the gland to theduct.

STRUCTURE OF THE MAMMALIAN GASTRIC GLANDS. 3 8 9

FIGS. 8J 9, and 10 are sections from the lowest portion of the pjloric glandof the cat in diiferent secretion phases, and stained in iiuliilin and eosin.

FlQ. 8.—From an animal after twenty-four hours' fast.

F I G . 9.—From an animal killed six hours after feeding.

F I G . 10.—From an animal killed twelve hours after sponge-feeding.

FIG. 11.—Body of fundus gland of dog after a fast of twenty-seven hours ;

htematoxylin and eosin.

F IG , 12.—The same from a digesting dog; the cells here contain an un-usually large amount of prozymogen-holding protoplasm.

F I G . 13.—Cells from the pyloric gland of the dog after twenty-seven hours'fast; indulin and eosin.

FIG. 14.—Cells from the pyloricgland of the dog twelve hours after sponge-feeding; iiidulin and eosin.

>AlKsM. 29.