( xvi ) 



the President's criticism of tlie Knight-Darwin law seemed 

 well-founded. Just as mutual fertility might be favoured 

 under selection, so no doubt it might be diminished or 

 abolished under isolation, by which selection is precluded. 

 Sterility in such cases was thus rather a consequence than a 

 cause. There must, however, be some reason for the numerous 

 contrivances which existed to ensure cross-fertilization. 



Mr. A. J. Chitty thought there were really two questions 

 involved in the discussion. (1) Did there exist in nature 

 anything corresponding to the one idea of species 1 (2) What 

 was the point at which living things ought to be considered 

 as distinct for the purposes of nomenclature and the arrange- 

 ment of collections 1 In practice it was necessary to take 

 some point, but if the history of life on the world was 

 represented by a tree as explained by Mr. Morice, he doubted 

 whether the idea of " species " had any counterpart in nature. 

 The distinctions between animals would vary to an almost 

 infinite extent, and would depend on the number of inter- 

 mediate forms which had fallen out, and he doubted whether 

 there was any precise point at which the distinctions became 

 different in kind. For study and collecting purposes some 

 such point must be chosen, but he was not prepai'ed to lay 

 down a rule where it should be placed. Where a large number 

 of intermediate forms had fallen out you found a distinction 

 which was what he understood was generally intended by the 

 term " specific distinction." Where this was not so you got 

 races and sub-species, and it Avas impossible that a collection 

 should represent the actual state of things in nature. 



Mr. H. J. Elwbs, Mr. W. E. Shaep, Dr. T. A. Chapman, 

 and other Fellows continued the discussion, and the President 

 said that he did not think that he ought to speak on the subject 

 after the anioimt of their time which he had occupied on the 

 occasion of the Anniversary Address. He would like, how- 

 ever, to remark that he had never conceived of the origin of a 

 species " from one ancestral pair," but always^rom the change 

 of masses rather than of individuals. He heartily agreed with 

 Mr. Morice in regarding a gen vis as formed by the further 

 differentiation of a single species, but it appeared to him that 

 it was the splitting of the single community into separate 



