248 NATURAL SCIENCE [October 



highly-developed and more differentiated organisms in animal or 

 vegetable kingdoms. While such men as Darwin and, to a less 

 extent, Romanes have occupied a more general position, the numer- 

 ous almost unconscious impressions that come to an investigator in 

 any branch of science, the little details of practical experience which 

 are rarely if at all jotted down, even by the most painstaking re- 

 corder, give, I believe, a general and correct, though usually uncon- 

 scious, colouring to all his work, original or otherwise, and are 

 largely influential in determining his convictions. 



It is to this colouring from different surroundings that I attri- 

 bute the positions taken up by the various evolutionists, and I 

 think, had it been possible for the Neo-Lamarckians and Neo- 

 Darwinians to have exchanged positions at the commencement of 

 their scientific studies, that both sets of investigators would have 

 materially altered their opinions. 



The conclusions drawn, both on theoretical and practical 

 grounds, from the study of the principal works of both sides, 

 seem to me to support the following propositions : — 



(1) That the simpler the organism, the greater the power of 



use-inheritance. 



(2) That the higher stages of evolution entail increased differ- 



entiation, and therefore increased difficulty of direct 

 adaptation to environment, and therefore increased de- 

 pendence on natural selection. 



(3) That high specialisation must be accompanied by a corre- 



spondingly increased stability, and, therefore, increased 

 difficulties in the action of use-inheritance, on account 

 of the increased dependence of those specialised parts on 

 each other. 



(4) Lastly that, with the increase of natural selection, the varia- 



tions must become increasingly adaptive. 



The second point has special reference to the theories of 

 heredity. To anyone who considers for a moment the immense 

 importance assigned to automatic, unconscious, and reflex actions 

 in Psychology, Physiology, and Pathology, and the large amount 

 which has been written on habit and its effect on the organism, 

 it must seem remarkable that so little importance has been given 

 to it in evolution and heredity. Erasmus Darwin considered that 

 as the embryo was made up of two portions which had formerly 

 belonged to its parents, it was reasonable to suppose that it would 

 to a large extent retain the habits of those parents. 



More lately, Professor Ewald Hering has extended this idea to 

 what he aptly defines as unconscious memory. His explanation of 

 heredity lies between the physiological and morphological schools. 



