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easy to determine from the limitations of such an article; yet it is an important consideration. The treatment of this part of the subject by its great exponent Haeckel' is clothed throughout with the causo-mechanical conception of the processes involved; here Haeckel confuses why' with 'how' in his efforts to strip phylogenesis of teleogical possibilities. In discussions on the significance of natural selection much confusion has crept in because of failure to discriminate between 'how' and 'why.' One is struck by the constant use of the latter word in Haeckel's History of Creation; over and over he contends that Darwin showed' why' the world inhabitants have undergone change. The natural selection theory attempts to show nothing but the mere method of the change, that is 'how'; Darwin practically said that the first cause of selection was unknown. The 'why' is of course throughout given a bearing on the broad question of a plan or purpose in nature.

In our present quest there must needs be little to occupy our attention in the views concerning initial forms of life. No one of the exponents of evolution of note confines himself to one original type of living form. Haeckel, a pure monist, premises one or a few; Darwin allows four or five, and so on to those who contend that there must have been several. We are not discussing the mechanical or monistic view of the appearance of these forms by archigony; nor are we considering the various arguments advanced for the impossibility of spontaneous generation, or its conformity with the Catholic point of view by giving the word spontaneous a different significance. The question is: May we accept these (several if necessary) primitive forms, primitive in type and ontogenetically immature, as owing their origin to supernatural agency (creation) and consisting of living matter (protoplasm), a complex chemical compound endowed by the Creator with extraordinary powers of metamorphosis and expansion? May we conceive that a process of evolution brought this matter and these living types to a state of perfection-the human body-adapted for the implantation of a rational soul? This, it must be repeated, yields nothing to psychic evolution, or pseudo-animist variant of it. Father Agius is concerned with the claims of the zoologist, who 'ignores psychic factors,' and makes no reference to those of the mental evolutionist, who is in reality a more

1 History of Creation.

formidable opponent. A recent work of the Spaniard, Ingenieros, Psychologie Biologique (French translation), gives an exhaustive account of this aspect of the subject, experimental and comparative psychology, etc., and their bearing on it. It is sufficient to remark here that observations and facts of a purely scientific kind are faithfully given by him, but the application of them and resulting conclusions are for the most part quite erroneous.

Pending a reply to the question set out for primary species we may consider further details in Darwin's theory, though our considerations are bound to be affected by the nature of the reply. He first laid stress on the limits existing to the supply of material in nature for the maintenance of life; but the multiplication of living organisms is so extensive that more of these are produced than could possibly be accommodated, and therefore there is a constant struggle going on between them for the means of life. In this struggle for existence the strong survive; they are best fitted to acquire the necessary sustenance, while the others die for lack of it or are killed off. The surplus in nature is limited by destruction of the seed or of individuals, the chief checks to the increase of which are parasites, epidemics, weather, want, preying animals. Wallace, independently of Darwin, hit upon the theory of natural selection; it was the latter who developed it.

Adaptation to environment by variation, that is change of structure of the animal in changed surroundings-direct variation or change in the offspring only, at least visible change-indirect variation-involving also change of habit and of function, is an essential process in the theory. It is the property supposed to enable the animal to react so as to fit it for the struggle. It would be of little consequence as an argument for the mutability of species, were the changes thus acquired by a particular individual or generation not transmitted to subsequent generations. The promulgator of the theory naturally included this, but was careful to note the marked conservative tendency of inheritance or preservation of original characters working pari passu with it— like tending to produce like. These inherited characters are sometimes noted in atavism, where the individual resembles a remote ancestor.

A few examples of direct variation may here be cited. The axolotl, normally a water animal, may leave this habitat and take to the land; in such a case it has been VOL. XV-4

known to grow lungs to replace gills. Tadpoles, on leaving the water, grow air-breathing apparatus also. The triton, like the tadpole, grows lungs, and its gills disappear when it goes into the air, but if taken and shut up in a tank at this time, instead of being allowed to go into the open air, the gills remain and no lungs appear; it remains like the other salamanders, which naturally never change their waterbreathing apparatus. Degenerate changes in parasites are of the same order-structural-as well as degeneration of wings, muscles, etc. Numerous instances of such change are to be seen both in nature and as a result of artificial selection. Artificial selection is the term given to the efforts of farmers and others who improve stock by special breeding methods, as well as to those of the experimental worker, like Darwin, for instance, who claimed to have brought about some striking structural changes in pigeons in the course of a few generations.

Habit variation is a well-known phenomenon. Animals adapt themselves readily to new conditions, and where this fails they succumb; in captivity some species are much more casily adaptable than others. Adaptation of function is much allied. An example of this recently came under the writer's notice in Paris. Professor Lapicque, of the Sorbonne, was performing experiments with sea-weed to prepare it for horses' food. Having bleached the weed, he tried it on the animals; at the end of six days he was about to despair of success, because the material was not being digested, but he then noticed that some of it was; persevering with the thing he found that the horses digested it in full after about a fortnight's training,' and from the condition of the animals so fed, and the work which they were able to perform, no doubt remained that it was well assimilated and acted as an excellent food. The digestive apparatus of the horse became adapted to the new function.

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Professor Adami, in the Croonian Lectures, drew attention to the well-known facts of immunity from diseases. In this we have an adaptation of a new property, not the mere evoking of a present one or the persistence of a chance variation. All these and similar instances of variation must be conceded; it is a different problem, however, when it comes to the transmission to offspring.

Stockhard's experiments at the Cornell University and

1 British Medical Journal, June 30, 1917.

others are supposed to supply evidence of transmission of acquired characters. Stockhard subjected male guinea pigs to the fumes of alcohol and then tried breeding from them. From twenty-four matings there were only five litters with a total offspring of twelve; of the twelve, seven died in convulsions and the rest at two months were half the normal size. When these last were mated the offspring were still worse, and so on to the fourth generation. It is of small import that the transmitted defect is not always precisely the same as in the parent. It is, of course, not in accord with the claim that only useful variation shows a marked tendency to transmission. There is no need to go over the old stock arguments for and against this inheritance of acquired characters. Artificial selection-one of the chief phenomena favouring it-does give some surprising results in altering species in the course of a few generations. The evidence derived from it, however, is principally that of intensification of existing properties rather than that of acquirement of new. Adami has succeeded in producing from harmless microbes a new race of poisonous germs by altering the conditions of their growth. The innocent germs of the natural form are innocuous, but after a few generations in changed circumstances they produce disease, and maintain that virulent character in subsequent generations.

Habit variation sometimes bears a peculiar relationship to structure. Upland geese have webbed feet, but they never take to water; they have changed their habitat and habits. Birds like the diving thrush, on the other hand, without webbed feet, take to the water in search of food. Certainly this habit variation is maintained in subsequent generations. A case of habit variation which is of great interest is that of maintaining and adapting to all exigencies a sudden artificially produced change in an organism, not of structure but of transposition. It is seen in the hydra, a small freshwater animal, which consists of a simple tube-like body, a head and a cul-de-sac tail end. The interior surface of this tube is for digestion, the exterior for respiration. The hydra can be turned inside out, and in this condition it remains the surface which formerly digested now taking on the function of respiration, and the respiratory surface digesting. Now the view of natural selectionists is that did such a change prove useful one could conceive its becoming permanent in the species.

All readers of Darwin are not in agreement as to the

significance of the theory, either from a purely scientific standpoint or in its bearing on ulterior views of the universe and supernatural influence. There are different forms of Darwinism. For Spencer and his congeners it is the coping stone to the edifice of mechanism or materialism in science; they would have it clinch and perpetuate the view that everything is explained by environment. According to this, environment is the active agent, the animal being merely passive in its responses. But for others, who accept the theory of the struggle for survival, it reveals a purpose and refutes mechanism; the vital theory connotes a purposive reaction on the part of the animal to extraneous stimuli, a reaction which, in its turn, connotes a priori Intelligence for the plan. The term Darwinism should more strictly be Spencerism. Darwin certainly, when he wrote the Origin of Species, did not consider natural selection as bearing the non-telic character bestowed upon it by later exploiters. He was no scoffer, and frequently referred to the Creator in his work. 'To my mind,' he says, 'it accords better with what we know of the laws impressed on matter by the Creator that the production of the past and present inhabitants of the world should have been due to secondary causes like those determining the birth and death of the individual.'1 Wasmann carefully distinguishes between Darwinism in its restricted sense, which is Darwin's theory of natural selection, and its wider sense, which is the generalisation of that theory to a so-called Darwinian cosmogony, which must be rejected absolutely. The extension of natural selection to monism is a mischievous act committed in the name of science.2

Criticism of the theory is confined to a few heads. Firstly, the absence of transitional forms is against the mutability view. Secondly, the acquirement and modification of instinct make a complex problem for explanation. Thirdly, there was the difficulty of accounting for the sterility of hybrids with the fertility of mongrels; and lastly, how great complexity in some organs with great simplicity in others are to be reckoned as products of the same moulding process -the eye, for instance, as compared with the tail. The absence of linking forms is attributed by adherents to defects in the geological record, and to extinction, the tendency to which, in the narrow belts where species mix, is great, while the tendency to variation is slight in this junctional

1 Origin of Species, p. 449.

2 Loc. cit. p. 160.

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