(7 £0" 73) [xvi 
Somewhere among the intermediate stages the line must be 
drawn, and when drawn it would still be arbitrary. 
On the question of sterility of first crosses and of hybrids, 
the President’s criticism of the 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. Currry thought there were really two questions 
involved in the discussion. (1) Did there exist in nature 
anything corresponding to the one idea of species? (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! 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 prepared 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 was impossible that a collection 
should represent the actual state of things in nature. 
Mr. H. J. Erwes, Mr. W. E. SHarp, 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 amount 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 from the change 
of masses rather than of individuals. He heartily agreed with 
