C O R R E S P O N D E N C E

The Sources of Some Ethological Notions SIR,

At a recent Conference on Group Processes (1955) a number of notions current, or recently current, in comparative ethology were con- sidered. As I am wrongly credited with one of them, it seems worth while tracing their history, if not to their origins, then some way back into the past.

On p. 182 Dr. K. Z. Lorenz makes the follow- ing statements regarding the differences in the threshold of stimulation needed to evoke instinctive movements. "The first assumption is, in both cases, that 'something' is accumulated during the rest period of the activity which is destroyed during its performance. Holst thought that this 'something' might be humoral, a theory which was independently proposed by J. B. S. Haldane at the symposium on instinct recently in Paris."

At that symposium I made no claim for originality in this matter. I pointed out that the notion of a reservoir which was exhausted by activity and then filled up again, put forward by Lorenz (1950, and earlier) was due to McDougall (1923). If [ remember I first met with it in his lectures in 1913.

McDougall, in the book cited, devoted three pages (107-109) to this hypothesis. He discussed whether it was better to postulate one reservoir or a separate reservoir for each instinct. He finally produced the following "mechanical analogy." "Each instinct is represented by (1) a chamber within which a process of fer- mentation or other chemical change liberates a gas, which accumulates under pressure. The several chambers communicate with one another by fine channels through which the gas can pass against considerable friction, when the pressure in any two chambers is different. (2) Each chamber has an outlet which branches into a complex system of pipes leading to a group of executive organs (nerves leading to muscles and glands). (3) This outlet is closed by a door or sluice-gate provided with a lock of more or less complex pattern peculiar to itself (in some cases it is a series of locks rather than a single one). This door is never quite gas-tight; gas leaks through, and leaks in larger quantity the higher its pressure in the chamber (appetite and the restlessness in which it is expressed). When the key is turned, the door swings open and the gas, issuing along the many channels,

sets in action the various mechanisms to which it is led . . . The key is the sensory-pattern pre- sented by the specific object of the instinct (e.g. the nightingale's song, the peacock's tail)." He continued that the analogy might be im- proved by replacing the locked door by a spring valve, actuated by a lever held back by a series of stops. "The complete depression of the lever and the fullest opening of the valve occur only when a certain combination of keys is struck; the striking of some of these keys will permit a partial depression of the lever." He was inclined to locate the sluice gates in the thalamus. McDougall clearly borrowed some of his ideas from Descartes, who located the sluice gates in the pineal gland.

Lorenz' (1950) model was very similar to McDougall's, but he did not admit communi- cation between different reservoirs. McDougall postulated such communication to allow for what are now called displacement activities. Lorenz was evidently unaware of McDougall's priority. The works of Drees (1952) on jumping spiders suggests that it might be better to think in terms of several sluice-gates for one reservoir. Zupancic (1953) has further developed the theory, and thinks that the destruction of the substance stored in the reservoir yields the energy which starts nervous impulses. In particular carbon dioxide is destroyed by carbonic anhydrase in the respiratory centre. I must emphasise that McDougall, though a vitalist, did not regard this biochemical hypo- thesis as a metaphor. "We are naturally in- clined" he wrote, " to suppose that it is a case of conversion of potential energy, stored in the tissues in chemical form, into the free or active form, kinetic or electric or what not; and probably this view is correct. And we may legitimately speculate on the sources, the seat of storing and liberation, and the mode of direction of the liberated active energy, in purely physio- logical terms."

A casual reader of this part of the Macy Foundation Discussion might think that Dr. Lorenz did not himself believe in the reservoir theory. However on p. 147 Dr. Lehrman sug- gested that "Dr. Lorenz's hydraulic models might be misleading," and added "The releasing mechanism is described as if it were a set of valves." To which Dr. Lorenz replied "That is exactly what it is."

162

C O R R E S P O N D E N C E 163

The McDougall-Lorenz reservoir hypothesis was discussed for some fifteen pages, by which time it had become "Haldane's assumption." In Paris I illustrated it from the relation of carbon dioxide to the respiratory centre. A better example might have been the potassium in a nerve fibre. When an impulse passes along a fibre the membrane becomes permeable, potas- sium flows out, and sodium flows in. An im- portant part, perhaps the essential part, of the recovery process is the activity of a "sodium pump" which reverses this process. It is probable, but not certain, that the same thing happens when the cell body of a neuron is stimulated. But I cannot regard an increase in the permeabil- ity of a cell membrane as being, in Dr. Lorenz' words "exactly" the opening of a valve. This is a metaphor. The accumulation of a substance may not be a metaphor.

I suggested, and still suggest, that McDougall and Lorenz w~re quite right in proposing that the readiness of a "centre" or small volume of the nervous system to produce nervous impulses depends on the concentration in it of some substance or substances. I think it un- likely that they are often as simple as carbon dioxide or potassium. They might for example be precursors of acetyl-choline, or the various neuron-stimulating compounds which have been found in different parts of the brain stem (v. Vogt, 1954) for example serotonin. It seems to me more likely that activity reduces the amount of such a substance than that it acts by "the reduction of tissue tension," as Lehrman (Group Processes, p. 190) suggested. I do not suppose that Professor yon Holst has any more wish than I to deny McDougall 's priority.

On pp. 181-182 of the same discussion Lorenz described the behaviour of a decapitated sea horse, whose spinal cord activates its dorsal fin. The passage which I quoted in the second para- graph continues as follows. "The second assump- tion is that the highest levels of brain function hold the continuous and spontaneous process under control under an inhibition which is removed only when the instinctive movement should be performed." Once again, this assump- tion is in no way novel. When I attended his lectures and demonstrations in 1920 and 1921, C. S. Sherrington made it as a matter of course. The most striking examples are "decerebrate rigidity," or decerebrate standing, which occurs in many mammals, and t h e intrauterine con- vulsions which are characteristic of anencephalic

human embryos, in which the cerebrum is replaced by vascular tissue but much of the brain stem may be formed. As I pointed out in Paris, the notion of release of function by removal or injury of cephalad parts of the nervous system is due to Hughlings Jackson (1931). This is the date of posthumous publication of his collected papers. He developed the notion on the basis of human clinical studies in the nineteenth century.

It seems reasonable to suppose that the centres for instinctive activities of mammals are mostly situated in the brain stem, where Hess and others have located some of them. They are normally inhibited by impulses coming down from the cortex. And since their release often depends on the perception of fairly complicated visual or auditory patterns it is probable that "innate releasing mechanisms" (McDougall 's "locks") are located in the cortex. This is not inconsistent with the fact that the early stages of an instinctive act often include complicated adjustments to the environment which involve the cortex as well as the brain-stem and thalamus. The final con- summatory act can usually be carried out even when the cortex has been removed.

I think that Jackson's work affords powerful support to Lorenz' notion of "releasers" and gives a more concrete idea of the neurological processes involved than is to be found in some recent ethological writings. Certainly the phrase "release of function" is to be found in Jackson's writings, though it may well have earlier sources, and is in fact implicit in such words as "self- control."

On p. 190 Dr. Lorenz spoke of the reinforce- ment of instinctive processes by the consum- matory act and in his concluding remarks (p. 288) said "Remember Wallace Craig's great discovery that the goal or end towards which the organism is striving, is not the survival value of its behaviour patterns, but the con- summatory act itself." He might have added that the goat was not the pleasure which (by analogy with human experience) is associated with some consummatory acts. Aristotle, in his Ethics, defined the word eudaimonia (generally trans- lated as happiness) as energeia anempodistos, which means an unimpeded endogenous activity. Precisely the same idea is found in the Indian Samkhya philosophy, almost certainly somewhat prior to Aristotle. For example in a section of the Bhagavad Gita which claims to expound this philosophy it is stated that the

164 T H E B R I T I S H J O U R N A L O F A N I M A L B E H A V I O U R , I V , 4

wise man should work without troubling whether or not his work brings a reward. This doctrine is rather pompously called the doctrine of non- attachment. Craig certainly deserves credit for showing that pigeons act according to the principles laid down by moralists for men, but hardly for discovering these principles.

The ethological school has discovered many important facts, but is not likely to commend itself by claiming credit for the notions of others. It is, in my opinion, more likely to be accepted into the general body of science and of philos- ophy if it shows that its data agree with, and help to support, previously enunciated theories.

J. B. S. HALDANE. Department of Biometry. University College, London.

R E F E R E N C E S Drees, O. (1952). Untersuchungen uber die angeborenen

Verhaltensweisen bei Springspinnen (Salticidae). Zeitschr. f . Tierpsyehol., 9, 169-207.

Group Processes (1955). Transactions of the first confer- ence. Edited by B. Schaffner, M.D. New York: Josiah Macy, Jr., Foundation.

Hughlings Jackson, J. (1931-2). Selected writings of John Hughlings Jackson. Vols. 1 and 2. Ed. J. Taylor. London: Hodder & Stoughton.

Lorenz, K. Z. (1950). The comparative method in studying innate behaviour patterns. Symp. Soc. exp. Biol., 4, 221-268.

McDougall, W. (1923). An Outline of Psychology. London: Methuen.

Vogt, M. (1954). The concentration of sympathin in different parts of the central nervous system under normal conditions and after the administration of drugs. J. Physiol., 123, 451-481.

Zupancic, A. O. (1953). The mode of action of acetyl- choline. A theory extended to a hypothesis on the mode of action of other biologically active sub- stances. Aeta physioL Scand., 29, 63-71.

B O O K R E V I E W S

Foreign Bird Keeping: Forty Years' Experience in their Breeding and Management. By EDWARD J. BOOSEV. Pp. 356, 43 plates in full colour, 73 monochrome plates. 63s.

The anthor and his partner, Mr. Alec Brooks- bank--who is responsible for the photographs-- have an extensive experience in the keeping and breeding of many "foreign birds," particularly since they founded the Keston Foreign Bird Farm in 1927. This works represents an accum- ulation of information that, in its form, would be hard to equal, and of particular interest are the many coloured plates reproduced from transparencies. This method of illustration has obvious advantages over the traditional artists' efforts, and it may be predicted that it will find ever increasing use in textbooks.

The main part of the work is divided into 4 sections, viz. (1) Waxbills, Finches and other seed-eaters (78 species); (2) Parrots and parrot- like birds (58 species); (3) insectivorous, omni- vorous and nectar feeders (33 species); and (4) Doves and Pigeons (9 species). Finally, there are two short chapters dealing with common diseases. Under each species are given notes relating to origin, description, feeding and, in appropriate instances, breeding.

The brief zoological names have been checked by Mr. John Yealland, but this, unfortunately for the scientific reader, is the limit of the documentation~ and references are not cited

to cover even the few quotations or authorities quoted in the text. It may reasonably be agreed that the book, which has a subjective flavour, is intended for quite a different public, but further information of this kind would have been helpful to those who might wish to employ some of the species for behavioural or other studies.

The publishers are to be congratulated on the production and in view of the number of illustrations the price seems most reasonable.

A.N.W.

Diseases of Fishes. By C. VAN DUIJN, Jnr. London: Poultry World for "Water Life." 1956. Pp. 188, fully illustrated. 14s. 6d.

This would appear to be a most useful book, and although it may be a little overshadowed by the almost simultaneous appearance of Schaperclaus's large volume, Fisch-Krankheiten, it nevertheless merits the high praise that the publishers have bestowed upon it and should be equally useful to fish-keepers and laboratory workers alike. The insertion of references is a pleasing feature and adds greatly to the value of many sections, while the illustrations (mostly photographs and line drawings) are for the most part very good indeed.

A,N.W,