Summary

Coloration of butterflies; brilliantly coloured females.

Commends CD on his paper on specific differences in Primula [J. Proc. Linn. Soc. Lond. (Bot.) 10 (1869): 437–54; reprinted and revised in Forms of flowers] as a test-case proving origin of real species.

Summary

On his Primula paper for the Linnean Society ["On the specific difference between Primula veris, Brit. Fl. (var. officialis, Linn.), P. vulgaris, Brit. Fl. var. acaulis, Linn.), and P. elatior, Jacq.; and on the hybrid nature of the common oxlip; with supplementary remarks on naturally produced hybrids of the genus Verbascum", [officinalis!?] J. Linn. Soc. Lond. (Bot.) 10 (1869): 437–54].

Peacocks and sexual selection.

ARW’s sterility argument has driven CD’s sons half-mad.

Summary

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.

Summary

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.

Summary

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.

Summary

There are so many doubtful points on the problems relating to sterility that they will never agree.

Summary

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.

Summary

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].

Summary

Warns ARW of dubious character of list of European alpine genera and species in volcanoes of Hawaii. Problems of geographical distribution in oceanic islands.

Summary

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.

Summary

Various topics related to sexual selection: sexual differences, sexual preferences, coloration.

Summary

More on CD’s objections to ARW’s views on protection and natural selection.

Sexual selection.

Summary

Answers CD’s objection [see 6121 and 6146] about sexual differences and protective colouring. Summarises his theory of colour in nature.

Summary

Criticism of ARW for too little esteem of the role of sexual selection as agent in giving colour.

Response to other topics.

Summary

The problem of sterility, and its relation to natural selection.

George Bentham’s support of Darwinism.

Summary

The problem of dimorphic plants and their fertility.

Summary

On triumph of "Darwinianism".

Discussion of their differences on subject of protection.

Summary

Accepts invitation.

Summary

ARW’s wife will accompany him to Down.