Showing 61–80 of 100 items
On sterility of natural species and natural selection. Closely allied forms from adjacent islands offer best chance of finding good species fertile inter se.
Problem of minute variations and sexual selection.
On problem of sterility, CD cannot persuade himself that it has been gained by natural selection.
On sexual selection and minute variations, he tends to agree with ARW. Sends George Darwin’s notes on ARW’s argument.
Returns George Darwin’s criticisms of his notes on sterility and sends further notes in reply. Since there are degrees of sterility between varieties, "is it not probable that natural selection can accumulate these variations?" Varieties that are adapted to new conditions could then survive and form new species without being isolated.
There are so many doubtful points on the problems relating to sterility that they will never agree.
More on the "terrible problem" of natural selection and sterility. CD’s reasons for disagreeing with ARW. CD analyses and answers ARW in detail in defence of his conclusion that sterility cannot be increased through natural selection.
If CD is not convinced by his notes on sterility, ARW has little doubt that he is wrong. In fact he was only half-convinced by his own arguments.
Modifies his first proposition [a species varies occasionally in two directions, but owing to free inter-crossing the variations never increase] and further discusses the subject.
Encloses Berthold Seemann’s notes on flora of the Hawaiian Islands. Presence of European alpine species in Hawaiian volcanoes is a "hard nut" for geographical distribution [but see ARW’s Island life (1880), p. 323].
Warns ARW of dubious character of list of European alpine genera and species in volcanoes of Hawaii. Problems of geographical distribution in oceanic islands.
Admires ARW’s "Theory of birds’ nests" [J. Travel & Nat. Hist. 1 (1868): 73].
Discusses their respective views on birds’ nests, sexual selection, and protection.
Asks why, if brilliant colours of female butterflies are result of protective mimicry, do not males become equally brilliant? CD believes variation in females alone accounts for it, rather than protection.
Various topics related to sexual selection: sexual differences, sexual preferences, coloration.
More on CD’s objections to ARW’s views on protection and natural selection.
Sexual selection.
Answers CD’s objection [see 6121 and 6146] about sexual differences and protective colouring. Summarises his theory of colour in nature.
Criticism of ARW for too little esteem of the role of sexual selection as agent in giving colour.
Response to other topics.
The problem of sterility, and its relation to natural selection.
George Bentham’s support of Darwinism.
The problem of dimorphic plants and their fertility.
On triumph of "Darwinianism".
Discussion of their differences on subject of protection.
Accepts invitation.
ARW’s wife will accompany him to Down.
On sounds produced by Euchirus longimanus beetle. Sends a pair by post.
CD’s oscillating views relating to protection and sexual selection.
Submits a 15–point argument against CD’s views on the coloration of female birds and insects.
