20 REPORT — 1889. 



mediate form is often of immense interest as indicating the path along- 

 which the modification from one apparently distinct form to another may 

 have taken place. 



Though palajontology may be appealed to in support of the conclusion 

 that modifications have taken place as time advanced, it can scarcely 

 afford any help in solving the more difficult problems which still remain 

 as to the methods by which the changes have been brought about. 



Ever since the publication of what has been truly described as the 

 'creation of modern natural history,' Darwin's work on the ' Origin of 

 Species,' there has been no little controversy as to how far all the modi- 

 fications of living forms can be accounted for by the principle of natural 

 selection or preservation of variations best adapted for their surrounding 

 conditions, or whether any, and if so what, other factors have taken pari. 

 in the process of organic evolution. 



It certainly cannot be said that in these later times the controversy 

 has ended. Indeed those who are acquainted with scientific literatui'e 

 must know that notes struck at the last annual meeting of this Associatiou 

 produced a series of reverberations, the echoes of which have hardly yet 

 died away. 



Within the last few months also two important works have appeared 

 in our country, which have placed in an accessible and popular form many 

 of the data upon which the most prevalent views on the subject are based. 



The first is ' Darwinism : an Exposition of the Theory of Natural 

 Selection, with some of its Applications,' by Alfred Russel Wallace. No 

 one could be found so competent to give such an exposition of the theory 

 as one who was, simultaneously with Darwin, its independent originator, 

 but who, by the title he has chosen no less than by the contents of the 

 book, has, with rare modesty and self-abnegation, transferred to his fellow- 

 labourer all the merit of the discovery of what he evidently looks upon 

 as a principle of overwhelming importance in the economy of nature •, 

 ' supreme,' indeed, he says, ' to an extent which even Darwin himself 

 hesitated to claim for it.' 



The other work I refer to is the English translation of the remark- 

 able ' Essays upon Heredity and Kindred Biological Problems,' by Di*. 

 August Weismann, published at the Oxford Clarendon Press, in which is 

 fully discussed the very important but still open question — a question 

 which was brought into prominence at our meeting at Manchester two 

 years ago — of the transmission or non-transmission to the offspring of 

 characters acquired during the lifetime of the parent. 



It is generally recognised that it is one of the main elements of Dar- 

 win's, as well as of every other theory of evolution, that there is in every 

 individual organic being an innate tendency to vary from the standard 

 of its predecessors, but that this tendency is usually kept under the 

 sternest control by the opposite tendency to resemble them, a force to 

 which the terms ' heredity ' and ' atavism ' are applied. The causes. 



