124 



NATURE 



{June 7, 1888 



details, from their complexity or from their intricacy, we 

 are ignorant. 



From his study of the life-conditions of some lizards, 

 Dr. Eimer has reached the conclusion that at any given 

 time variations occur only in a few definite directions. 

 These directions depend on inner constitutional causes. 

 The variations are produced by the direct action of the 

 environment, are always transmitted, and when accumu- 

 lated, become the inner constitutional cause determining 

 the direction in which the organism will respond to new 

 stimuli. In old males which have been subjected for a 

 longer time than other forms to the environment there is 

 a tendency to the appearance of new characters. These 

 show the direction in which species-variation is going to 

 take place. Not only does the ontogeny repeat the 

 phylogeny in a condensed form, but the later stages of 

 the ontogeny are prophetic of the new phylogeny. Varia- 

 tion, so directed and limited, assimilation causing growth, 

 and reproduction or discontinuous growth, are the chief 

 laws of organic growth. 



Suppose a primitive undifferentiated plasma capable of 

 responding to stimuli of heat, light, moisture, &c. In 

 response to the action of the environment ever slightly 

 varied in such details, various conditions would " crystal- 

 lize out " of the plasma, just as from a homogeneous 

 inorganic mass crystals form in varied groups. As the 

 organic world continued to grow, this original differentia- 

 tion would increase. With increase of complexity due to 

 the storage in each generation of the complete effect of 

 the environment on each stage of the phylogeny, the 

 different directions in which forms were developing would 

 become more different. Each new character appearing 

 would through correlation influence the whole organism. 

 Allow a little to natural selection and a little to the results 

 of sexual mingling, and the varied species, orders, and 

 classes into which the organic world can now be divided 

 appear as the inevitable result of its mode of growth. 

 There is no need to search for intermediate forms : they 

 may never have existed. As the branching of a tree is 

 the natural consequence of its mode of growth, so is 

 separation and isolation inevitable in the whole organic 

 world. 



The two crucial points in Dr. Eimer's theory are his 

 view of the action of the environment and his extreme 

 Lamarckian acceptance of the transmission of acquired 

 characters. Probably he is correct in his supposition that 

 the extent of the direct action of the environment has as 

 yet been unappreciated. Many characters hitherto unex- 

 plained may come to be referred to direct action, and 

 experiment only can determine its scope. But it is no 

 explanation of the presence of chlorophyll to refer it with 

 the author to the continued action of sunlight upon proto- 

 plasm. And still less is it an explanation of the difference 

 between queen and worker bee to refer it to the difference 

 in their food. But indeed in this latter case the refutation 

 of the author is easy. The neuter is not a different kind 

 of bee produced by a different kind of food. It is merely 

 an arrested queen — a queen that has not become some- 

 thing else on account of a different diet, but a queen that 

 is not quite a queen because it has not had enough to 

 eat. That this is the true state of the case is apparent 

 from the less specialized colonies of wasps. There the 

 queen in spring lays female eggs, and has herself to forage 



for the whole brood. As a result the young do not get 

 enough to eat, and the development of their sexual organs 

 is arrested. They in turn help to feed the next brood, 

 the individuals of which reach a further state of develop- 

 ment. As the summer wears on, the ever-increasing 

 band of workers bring in an increasing supply of food, till 

 finally a condition is reached when there is enough food 

 to make perfect females of a whole brood. Clearly the 

 bee colony, with its sharper distinction between neuter 

 and queen, is merely a specialization of this condition. It 

 is but a verbal explanation of the difference between 

 queen and neuter to refer it to the direct action of food 

 upon the organism. Moreover, to explain the condition 

 of things even in the wasp colony, natural selection is 

 necessary. Obviously, insufficient food would arrest 

 general development as well as sexual development, and 

 natural selection acting on variations naturally arising 

 had to select those whose genitalia suffered most with 

 least detriment to general powers. From the many in- 

 teresting cases adduced by the author, this one has been 

 selected because it is fairly typical of the slight grounds 

 on which he refers important characters to the direct 

 action of the physical environment. 



As for the inheritance of acquired characters, it may 

 be said at once that Dr. Eimer has added nothing 

 of importance to the controversy. He certainly has 

 adduced a few isolated cases that seem to be explained 

 best on this theory ; and were the inheritance of acquired 

 characters merely of incidental value to his argument, his 

 easy acceptance of the traditional view might avoid 

 criticism. But when it is said that the direct action 

 of the environment, together with inner constitutional 

 causes, produces varieties and species, and that these 

 inner constitutional causes that determine the direction 

 of variation are merely a summation of direct action, a 

 summation effected by inheritance, we perceive at once 

 that a new and all-important role is assigned to heredity. 

 There is no attempt to meet the serious theoretical diffi- 

 culties involved in every conception of the mechanism ot 

 the inheritance of acquired characters : there is no 

 adequate attempt to establish the fact. Were it possible 

 and were it true, undoubtedly it would be, as Dr. Eimer 

 in elaborate and learned detail has shown, of immense 

 importance. But to prove its possibility or truth Dr. 

 Eimer has done little or nothing. 



Dr. Eimer appears to have mistaken a generalized 

 expression of the process of evolution for an explanation 

 of it. Natural selection acts at a time only on the one or 

 two characters which the environment temporarily ele- 

 vates into criteria of existence. But, as these change, 

 there are changed with them a vast multitude of minor 

 characters — in a word, there results what the author 

 happily calls " kaleidoscopic variation." These changes 

 can be referred only indirectly to selection, though they 

 may play no inconsiderable part in determining the 

 appearance of the organism. With all these variations 

 are correlated variations in the results produced by the 

 direct physical action of the environment. 



Dr. Eimer has concentrated his attention on these 

 secondary and certainly neglected changes, and his 

 theory is a statement of their course. But he has brought 

 forward no motive power to take the place of natural 

 selection in determining the ruling changes ; and there- 



