LixxEAX sociErr OF Loxroy. 93 



tliemselves what miojht have happened if sexual differentiation had 

 never arisen and the complications introduced thereby had never 

 occurred. He believed that divergent evolution would still have 

 taken place in a tree-like manner under the influence of chantring 

 environment, and that species would have become separated iroiu 

 one another by the dying out of connecting links, as Charles 

 Darwin supposed. He called attention to the c;ise of isolated 

 species which liad undergone evolution on oceanic islands, such as 

 the flightless Dodo of Mauritius and the Solitaire of Eodriguez. 

 8uch species were generally believed to have oiiginated from 

 ancestors whicli had reached their respective islands by flight and 

 which must have been very difl:erent from their descendants. It 

 was hardly possible that there had been any opportuuity in such 

 cases for crossing between distinct varieties or species, and vet it 

 would be absurd to say that the flightless birds, which had gradu- 

 ally lost the povver of flight as the result of changed habits in 

 their new environment, belonged to the same species as the 

 ancestral forms which first reached the islands. He thought that 

 the innumerable more or less clearly recognizable forms that could 

 undoubtedly be produced by hybridization played but a small part 

 in evolution, and that it did not very much matter whether they 

 were termed species or not. 



Sir Francis Darwix. I should be glad to be allowed to say a 

 few words, since I have a hereditary interest iu any evolutionary 

 disi-ussion held in this room. 



Those who know Dr. Lotsy or his writings will not need to be 

 told that his paper is in no sense hostile either to Darwinism or 

 to the author of the Darwinian theory. I should like to thank 

 him for his attitude in regard to my father. 



As far as I can judge, Dr. Lotsy has made a fair and striking 

 statement of his theory; but I have not the detailed knowledge 

 of genetics needed to form a critical judgment of his views. 



A point that interests me especially is the bearing of Dr. Lotsy's 

 theory on the adaptation of flowers to insect visitors. 



A'ariation is to a species what movement is to an individual, 

 since without change of form, temporary or permanent, no 

 response can be made to new conditions. The life of a species 

 must depend on appropriate variation as much as that of an 

 individual on movements. If Lotsy is right, and variation 

 depends on crossing, there is obviously a powerful selective force 

 at work on such floral structures as favour cross-fertilization. 

 This is a subject which Dr. Lotsy has referred to in the proofs 

 of his French paper, which he was good enough to show me. 



Dr. A. B. Eexdle pointed out that the sudden appearance of 

 a large number of new species as the result of segregation 

 following a cross suggested the origin of genera rather than of 

 species. 



