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Darwin Correspondence Project

DCP-LETT-7491

From G. R. Crotch   19 [February 1871]1

Cambridge.

19th.

Dear Sir

Allow me to thank you for your book—2 what a blessing to have the edges cut— you will take off 5/c of unpopularity by that—a new form of selection—3 I have just read Mivartts book—4 he degenerates so rapidly after the middle as to be quite curious, some points are well urged—but reiteration is tedious especially of cuts. There is a tendency to justify Pangenesis up here & to bring mathematical illustrations of it which seem good—5 Wallace’s address on Madeira will not convince me at any rate— he misapprehends the point besides making gross mistakes—(e.g. apterous Rhizotrogus)—my idea being that the islands if connected were of course then summits of mountains—6 now the apterous genera he does not find there are almost all denizens of the low sandy flats by the sea & rivers of Spain & Morocco—which would not be able to go upward as the land sank & hence were destroyed— the few apterous genera in common, Tarphius—Acalles—etc are precisely found in the Pyreneees the Apennines etc—& are mountain things—7 that Colonization has played a large part I don’t doubt, but there is evidence I think of connection—

in pressing the Tarphius question he forgets the Indian Tarphii from the Himalayas also— The absence of certain groups as Carabus, Rhizotrogus etc is the less unaccountable—as they all occur in Canary—which is otherwise so similar— There also the low sandy islets which remain are provided with precisely all those genera of Pimelia Brachycerus etc.8 The azores are better for him but I consider they have hardly been collected—& certainly that nearly all their fauna is gone from them now.9

Yr GR Crotch

Footnotes

1
The month and year are established by the reference to Descent; CD received his presentation copies on 18 February 1871 (see letter to John Murray, 19 February [1871]).
2
Crotch’s name appears on CD’s presentation list for Descent (Appendix IV).
3
For CD’s preference for books sold with the pages cut, see Correspondence vol. 15, letter to Athenæum, 1 January 1867.
4
Crotch refers to On the genesis of species by St George Jackson Mivart (Mivart 1871a).
5
CD discussed his provisional hypothesis of pangenesis in Variation 2: 357–404. See also letter from Francis Galton, 9 January 1871, n. 1.
6
In his presidential address to the Entomological Society of London on 23 January 1871 (Wallace 1871a), Alfred Russel Wallace discussed whether the affinity of Coleoptera species on the Madeiran islands to those on the mainland indicated the existence of a former land-bridge. He himself thought that there had not been a land-bridge but that the insects common to the mainland and Madeira might have flown there, assisted by gales (ibid., p. lxiv). He based his argument partly on the absence of apterous forms common to Madeira and the mainland, despite the large number of apterous forms on Madeira; he listed Rhizotrogus as a wholly apterous genus that was absent from Madeira (ibid., p. lix). Crotch published criticisms of Wallace’s argument in Nature, 25 May 1871, pp. 65–6. He commented, ‘Of the very numerous European Rhizotrogi, only two Sicilian ones are apterous, so that its absence in Madeira tells either way.’
7
Tarphius and Acalles appeared on Wallace’s list of apterous genera peculiar to Madeira and other Atlantic islands, but allied to winged groups (Wallace 1871a, p. lxiii).
8
Carabus, Rhizotrogus, Pimelia, and Brachycerus appeared on Wallace’s list of apterous genera absent from Madeira (Wallace 1871a, p. lix).
9
In Nature, 25 May 1871, p. 65, Crotch commented that the ‘best island’ of the Azores, Pico, had not been investigated, and that in the others, almost all the original vegetation had disappeared.

Summary

Thanks for presentation copy of Descent.

Mivart’s Genesis of species [1871] is poor.

Mathematical illustrations of Pangenesis at Cambridge.

Wallace’s address on Madeira not convincing ["The President’s Address", Trans. R. Entomol. Soc. Lond. (1870): xliv–lxix; A. R. Wallace, Studies scientific and social (1900) 1: 250–66].

Letter details

Letter no.
DCP-LETT-7491
From
Crotch, G. R.
To
Darwin, C. R.
Sent from
Cambridge
Source of text
DAR 161: 273
Physical description
3pp

Please cite as

Darwin Correspondence Project, “Letter no. 7491,” accessed on 27 September 2016, http://www.darwinproject.ac.uk/DCP-LETT-7491

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