Lengthy analysis of sources of misunderstanding of natural selection. Advocacy of Spencer’s term "survival of the fittest" instead of "Natural Selection". ARW urges CD to stress frequency of variations.
Thanks CD for 4th ed. of Origin.
Discusses abnormal sexual characters produced by mimicry. ARW’s papers on the subject.
Agassiz’s "marvellous" Amazonian glacier theory.
Protective role of colours in caterpillars and butterflies. Sexual differences in colours of butterflies.
Pleased that CD approves his idea about caterpillars.
Thinks CD is right about selection in butterflies, but still believes protective adaptation has kept down colours of females.
Cannot yet see action of natural selection in forming the races of man.
ARW responds to CD’s list of queries about expression. Suggests acquiring informants through publishing the queries in newspapers. His doubts about their importance.
Has submitted caterpillar question to Entomological Society.
Describes his view on colour [of plumage] of males and females – i.e., that absence of brilliant colour in either sex is due to need for protection in incubation, rather than to sexual selection.
Never imagined that the facts about sexual selection could be new to CD. Thought fact that brightly coloured females build concealed nests and almost all those in which sexes differ remarkably build exposed nests might be new to him. Some problems remain. Sends his notes for CD to use if he wants.
CD is invited to see ARW’s collections at Bayswater.
ARW has written an answer to the Duke of Argyll and North British Review criticisms.
Informs CD of his reply to Argyll and the North British Review criticisms [in "Creation by law", Q. J. Sci. 4 (1867): 471–88]. Cites "the predicted Madagascar moth" and Angraecum sesquipedale.
Birth of Herbert Spencer Wallace.
Response to CD’s comments on "Creation by law" [see 5637].
The limits of variation discussed.
Thanks for Variation.
Reports work on his travel book [The Malay Archipelago (1869)].
Responds to CD’s queries on polygamy in birds and orang.
Discusses sexual selection and secondary characters; colours and sexual preference.
Expresses his admiration for Pangenesis; it is superior to Herbert Spencer’s theory.
ARW differs somewhat with CD’s chapter on causes of variability [ch. 22 in Variation]. Thinks several of CD’s arguments are unsound.
Briefly discusses how natural selection might aid in producing sterility between allied species.
Offers enclosure demonstrating that natural selection could produce sterility of hybrids.
More on Pangenesis and the inadequacy of H. Spencer’s approach.
On critical exchanges at the Linnean Society on natural selection and mimicry.
Roland Trimen’s paper on South African mimetic butterflies ["On some remarkable mimetic resemblances among African butterflies", Trans. Linn. Soc. Lond. 26 (1870): 497–523; read 5 Mar 1868].
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.
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.
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.
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].
Various topics related to sexual selection: sexual differences, sexual preferences, coloration.
Answers CD’s objection [see 6121 and 6146] about sexual differences and protective colouring. Summarises his theory of colour in nature.
