The History of Biological Theories

Condillac asserted further that animals only remain less developed than man because, their bodies being less perfect and their sense-organs less highly developed, their experience is necessarily less extensive. His ideas really represent a development of Locke's philosophy. Darwin was not acquainted with the work of Condillac, but he held the same popular ideas about the nature of the animal soul. When we read what he says about insect psychology we are reminded of the words of those collectors of insects who do not hesitate to kill the souls of their victims by using a bottle of alcohol, while all the time they talk in a somewhat affected manner about the wisdom of insects !

Darwin believed that all animals possess souls, something resembling the human soul ; he based his whole theory of sexual selection on this view, endowing animals with tastes similar to human tastes. He thinks that the lower animals have no such taste, for 'their sense organs are not sufficiently developed, nor is their mentality high enough, for them to be able to appreciate beauty, or any other kind of attractive mechanism, or to be capable of jealousy. Among the higher animals, however, sexual selection depends upon the will, the desire, and the choice of the opposite sex.'

These words show us that Darwin pictured animals as thinking, feeling, and acting as human beings do. He taught that instinct is an acquired character, and he dealt with it just as he would deal with any physical character whatsoever. Here he writes that he will not attempt to explain the origin of life, only to show how the differences between animals have arisen, as the result of natural selection. There he says that he is not attempting to explain the origin of the mental powers, only the diversities of instinct; he is convinced that these differences have arisen as the result of natural selection. Animals differ both in body and in mind. Both sets of qualities are inherited. If a mental quality proves of value in the struggle for existence, it will be retained, passed on to posterity, and increased. Thus new abilities arise in a quite mechanical manner. Only a few such mechanical factors are of influence. Animals with their lower intelli- gence have some degree of understanding ; realizing the advantage of some new habit they adopt it; a habit is formed which can be inherited it becomes an instinct.

Animal instinct was explained by Darwin in this fashion. These instincts, in spite of all their diversity as seen in domestic animals, in the cuckoo, among bees, in the ant- heap do not seem to have been regarded as very remark- able, either by Darwin or by his opponents. Darwin's method was used by other investigators. Among them Forel, the Swiss specialist on ants ; Buttel- Reepen (1900), who studied the life of the bee and the wasp; Wundt (1897), who, i his writings on the animal soul, paid particular attention to the pigeon's sense of hearing; Romanes (188$), in his book on the Intelligence of Animals; Lubbock (,1899), in his work on Instinct; W. A. Nageli (1896), tie physiologist; Wallace (1889), who looked upon all animals as very like human beings only less clever and* less experienced. Brehm's popular work on animals furnished tire best example of the applica- tion of this philosophy. . Anecdotes and travellers' tales, truth and falsehood, the most intellectual and the most trivial all confused together.

One man of science was strongly opposed to this an- thropomorphic psychology the entomologist Wasmann. Schooled in dogmatic theology and in scholastic philosophy, he sought, and not without some success, to apply the doctrines of St. Thomas Aquinas to the problems of com- parative psychology. Wasmann held that animal instinct is quite distinct from intelligence, nor is it to be regarded merely as a lower grade thereof fixed by inheritance (which was the view of the evolutionists).

In the various activities of the organism he distinguished between : (a) Purposeful reflex actions, which depend solely on the nervous mechanism, and not on sensation, e.g. the action of the heart muscles, the peristaltic movements of the intestine during digestion, sneezing, &c. () Instinctive processes where sensations play their part, and bring about purposeful activity. Instinctive actions are 'Deeds which are the result of some sensuous desire. Their carrying out is controlled by the senses and organs of sense perception. These two qualities distinguish them from mere reflex actions.'

(c) Intelligent Actions. Here there is consciousness of the end to be attained. By this criterion we can distinguish between intelligent actions and merely instinctive ones. He further holds that intelligence consists merely of the power to relate ideas to one another, and to draw conclusions therefrom. To make his views clear Wasmann gives a detailed analysis of modern theories about the souls of animals. For him only man is 'intelligent'. Animals, even the highest, are dominated by instinct. They have no power of abstract thought, no capacity to formulate general ideas, no vision o the purpose of their actions. He also shows that the* views of the schoolmen may still be regarded as living ideas.. Though they may have been hidden beneath a mass of new theories they have survived till the present day.

Wasmann's work did not attract any attention from the scientific world. This was partly due to the conviction that scholasticism cannot possibly be reconciled with modern science, and partly to the fact that animal psycho- logists receive little training in philosophy ; but the chief cause was the realization that Wasmann had not arrived at his philosophical views by studying the facts of animal life. They did not represent his own individual expression of the results of his personal observation. It was felt that he had accepted scholasticism 'ready-made', and now was searching for facts to support his views.

When we note how uncertain Wasmann becomes when he leaves the well-beaten path of scholasticism we cannot help coming to the same conclusion. Wasmann agreed quite uncritically with modern scientists in believing that we can only understand the psyche of animals (and con- sequently of men too) by indirect means, by analogy with our own subjective life. Such an assumption is foreign to Aristotelian philosophy, and is the fruit of modern subjectivism. Aristotle and the scholastics believed as firmly in the psychical life of other men as they did in their own individual existence.

Wasmann's distinction between reflex actions and sensa- tions, according to the presence or absence of sensation, is not valid, as his opponents have shown. We have no scientific criterion of the subjective, so that we cannot use it as a basis of scientific classification. Further, since it would seem that intelligence develops out of instinct, and is not added to it as something different in essence, the gulf that Wasmann sets between the two cannot express the truth.

The Darwinian idea that animals possess a rudimentary intelligence probably contains a nucleus of truth. This truth, however, cannot be revealed by the primitive methods which were formerly adopted by the evolutionists. Wasmann's investigation of the different methods of obtaining knowledge seems to be based on actual observa- tion, and here again he concludes that there is a difference between animals and Man. He distinguishes between: (a) Individual learning: (i) by the instinctive exercise of inborn reflex mechanisms; (ii) through the senses; (iii) through sensual experience and the intelligent applica- tion of experience gained under familiar circumstances to new and unknown conditions.

(b) Learning by the aid of some external influence : (i) by stimulation of the imitative faculties ; (ii) by training ; (iii) by intelligent teaching. Only human beings are capable of learning in all the six ways. Animals may learn in the first way only, or in the first and fourth, or in the first, second, fourth, and fifth, depending on the degree of the animal's in- telligence. Fechner's suggestion that there is a parallelism between the psychical and the physical lies at the root of modern 'scientific 5 psychology. This psychology pictures the world as consisting of two kinds of realities the subjective, known only by the ego; and the world of objective realities, open to all.

If we are to speak of the soul at all it is identical with the former with subjective reality, while everything else is a part of the not-soul, of objective reality. These ideas bear a close relationship to those of Fechner; they are also akin to those of Helmholtz, and hence can even be connected with the earlier views held by Miiller. This modern psychology was really a development of the psychology of Descartes, but it also contained much that was pure anatomy facts relating to the structure of nerves, ganglia, cerebral centres, and the like. Much attention was also given to the construction of delicate apparatus. The soul was declared to be one attribute when not the sole one of living material, and to be the result of a definite nervous organization.

It was believed that, by skilful use of the scalpel, the microscope, and well-stained sections of the brain, all the problems of the soul could be solved. A curious version of this materialistic psychology was given by Gustav Jager (1880), an evolutionist of the old school. He studied the odours of various animals, and con- cluded that each individual emits a characteristic odour ; that, further, each family, each race, each order, each species, emits certain definite odoriferous substances. He suggested that these odours determine the relations of animals to one another. Predatory animals only follow prey who emit a smell which they like; the victims flee because they find the odour of their enemy unpleasant. He believed that sexual love, feelings of family or of racial unity, were founded on the diffusion and the detection of definite odoriferous substances. Fertilization is brought about first of all by odours emitted by egg and sperm respectively, an aura ovularis and seminalis.

Darwinists gave their approval to the theory. Jager, however, expressed his ideas in so paradoxical a fashion that they did not gain a very wide acceptance. He was often ridiculed. Nevertheless his ideas come into promi- nence every now and again although they did not exert any influence upon the scientific world. Mantegazza, the Italian writer, made use of them in his notorious book The Physiology of Love ; Bethe, the psychologist, returned to them in his endeavour to explain the machine-like precision exhibited by the lives of the bee and the ant ; he

was attempting to refute the prevailing views about the mentality of the lower animals views which he considered to be quite unscientific. Loeb used the same ideas more successfully in his endeavour to build up a 'comparative physiology' on a chemical basis. The work on 'tropisms' which was begun by Loeb and Sachs represents an important branch of comparative physiology, and forms an experimental introduction to comparative psychology. Jenning's 'Trial and Error Theory' occupies a position of some importance. He believes that many of those directed reactions to stimuli which are seen in both the plant and the animal kingdom, begin as blind gropings in any direction ; and that only when the external stimulus reaches a certain intensity do these movements become directed.

The science of comparative psychology has undergone considerable development in recent years. Many observers have gone back to the view that the animal is a kind of primitive man, and they have greatly added to our know- ledge of the animal soul by observation of the habits, instincts, even the 'sensible acts' of animals. To this type of work belongs Forel's work on Ants, Buttel-Reepen's on Bees, and Fabre's on insects. Much recent investiga- tion is directly related to the work of Loeb, and is physio- logical rather than psychological. This is particularly the case with the work of Bethe, Bohn, Uexkiill, and a whole series of workers on the so-called 'tropisms'. Modern experimental psychology of the American school has also derived its inspiration from Loeb, e.g. Jenning's very original studies, and the experiments of Yerkes, and others, Jenning's work led on to modern psychology of the behaviourist school. In this work, as developed, for example, by H. Watson and E. L. Thorndike, the intro- spective study of consciousness is rejected. They examine objective reactions only, both of men and of animals.

i. The Influence of Lamarck. AMARCK'S work cannot really compare in importance f with that of Darwin, although a vote taken at the present moment might be in favour of the opposite view. Look at the great historic movement caused by Darwin's work, see how noteworthy were both his supporters and his opponents, a Nageli, a Haeckel, or a Huxley; and compare this with that short-lived movement called Neo- Lamarckianism. Remember that this new movement would never have occurred without Darwin ; that it was not possible until Darwinism had lived out its time. Then we shall be able to judge rightly of the respective im- portance of Darwin and Lamarck. Darwin's book is so important in the history of science, because the author gives us there of his best. Every word of it breathes earnestness. His ideas have formed a part of the great stream of human thought. Full of doubts he gropes blindly for the truth, and when he believes, he believes with all the strength of conviction. Against this all that Lamarck has to give are a few suggestions. Nevertheless Lamarck's ideas have left their mark.

Darwin himself only saw in Lamarck's teaching vitalism under a somewhat thin disguise. He believed that his own point of view was quite different from that of his pre- decessor, and, as early as 1844, he pointed this out. 1 Nevertheless, he believed that the Lamarckian factor namely, the inheritance of acquired characters was of some importance. There were some workers who could not see any very great difference between the views of 1 His actual words were: 'Heaven forfend me from Lamarck's nonsense of "a tendency to progression", adaptations from the slow willing of animals, &c. But the conclusions I am led to are not widely different from his, tho' the means of change are wholly so.' Darwin's Life and Letters^ vol. ii, p. 23.

Lamarck and of Darwin. Darwin was often obliged to discuss this subject with Lyell and Huxley, and to assure them that the two views were far removed from each other. Many investigators were led back to Lamarck by a desire for historical accuracy, by an endeavour to see what connexion there was between Darwinism and older views ; among these were Haeckel and Huxley. Lamarck had always received much support in France ; so that it is not surprising that the French began to emphasize the importance of their fellow-countryman's work.

Since 1880 Lamarck's name has been referred to more and more. Roux's theory of functional adaptation, Weis- mann's denial of the inheritance of acquired characters, the gradual falling-off in the enthusiasm for Darwinism, all these factors helped to bring this about. In all this whirl of conflicting opinions it is noteworthy that no one seems to have turned back to the work of Erasmus Darwin, the grandfather of Darwin. He was writing before Lamarck, and in a much more original way, giving expression to very similar views about the origin of the organic world; his influence on Darwin was also a more direct one. How, then, are we to explain that to-day Lamarck is famous, but Erasmus Darwin is not ? Is it that we do not meet, in his work, those phrases so often cited in modern controversy ?

Lamarck did not state his theory at all clearly. His words suggest that there are blind mechanistic forces at work in nature, but his ideas are purely vitalistic. His followers continued the discussion, and there was the same lack of clear thinking among them. Even to-day, among those who discuss Lamarck's work, some consider that his philosophy is mechanistic, others hold it to be vitalistic. C. Detto (1904) holds that Lamarck is a vitalist, and rejects his views on that account. M. Kassowitz (1905), on the other hand, holds that his ideas are mechanistic, and cites them to controvert Neovitalism. A. Pauly (1905), again, declares that Lamarck, because of his vitalistic ideas, is a genius, and he dismisses his mechanistic theories,

declaring them to be illogical. J. P. Lotsy (1906), on the other hand, says that Lamarck was a mechanist, and a very able mechanist; his excursions into vitalism represent mere misapprehensions on his part, for which he must be forgiven! Pauly, following Lamarck, believes that it is the activity of the living organism which is all impor- tant; Lotsy also following, as he believes, in his foot- steps, emphasizes its passivity ! T. H. Morgan (1903) has deduced something quite new from Lamarck. He says that Lamarck's assertion was not that

'the desire of the animal for a particular part has led to the develop- ment of that part ; ... in reality he only maintained that the desire to use a particular organ to fulfill some want, led to its better development through exercise, and the result was inherited' (T. H. Morgan, Evolution and Adaptation, 1903). K. Goebel (1904) holds that Lamarck assumed the existence of certain evolutionary factors which are purely mental, and that in this he was mistaken.

G. Steinmann (1905) wants to introduce Lamarck's ideas into palaeontology. He discovers, in Lamarck 'an eye for history, an historical method, which placed him quite a hundred years in advance of his times, and enabled him to recog- nize laws which can, even now, only be properly understood when we have a background of history, and when they are considered in relation to this historical background* (Die geologiscben Grund- lagen der Abstammungskhre, 1908).

Steinmann, however, does not accept the vitalistic theory, and in his eyes Lamarck is a mechanist (although Steinmann never actually says this!). All that Weismann said about Lamarck was that he held the erroneous view that acquired characters can be inherited. We will cite Schopenhauer's view (Uber den Willen in der Natur, 1854) to cr wn this list of 'explanations' of Lamarck. All the workers we have named, however diverse their opinions about Lamarck, yet agreed that his im- portance lay in his assertion that organisms are all linked

up by their history. Schopenhauer, however, after saying that Lamarck was 'a first class zoologist', pointed out the correctness of his assumption that the structure of the animal is the result of its own endeavours. On the other hand (according to the same authority), he made a great mistake in assuming that there is any his- torical connexion between organisms! Kant, continued Schopenhauer, has banished such mistakes from Germany once and for all, together with the absurd and coarse French atomistics and the popular English physico- theological ideas.

To-day, many call themselves followers of Lamarck. Most of modern Neo-Lamarckism I arises, not from a con- viction that Lamarck was right, but from the feeling that Darwin was, in part at least, wrong. Many of this school simply oppose the idea of the will to the Darwinian idea of chance, soul to matter, understanding to mechanism, and function to structure. E. D. Cope (1840-97) an American palaeontologist who made a special study of vertebrates, held views about evolution similar to Lamarck's. These first appeared in scattered papers, and were only later collected and pub- lished in book form (1887). His writings were hardly noticed in Europe. In developing his theme he paid little attention to the views of other modern workers, nor did he seek any opportunity of explaining his ideas to other investigators. Hence his work was somewhat neglected.

Cope was a strict Lamarckian ; he thought evolution in the plant kingdom to be the result of the action of mecha- 1 The name Neo-Lamarckism was introduced by Packard. See his work Lamarck the Founder of Evolution, p. 396. G. Wolff, in his book Die Begrundung der Abstammungslebre (Munich, 1907), recognizes that Neo-Lamarckism represents the death-knell of the whole idea of evolution. It is, however, very difficult to understand how this able critic, having rejected the anatomical and embryological facts as insufficient to support the ideas of phylogeny, then suddenly finds a proof of the same in the so-called rudi- mentary organs (ibid., p. 24),

nical forces, and that the lower animals, together with certain very sensitive plants (e. g. Mimosa), are altered by continually recurring stimulation. It was his view that in higher forms of life an unconscious endeavour brings about evolution, while in the highest forms conscious striving stimulates to new kinds of activity. Natural selection plays its part in evolution. It is, however, not the only factor ; it only serves to the retention of useful elements and does not determine their origination.