From Asa Gray 7 July 1857
Summary
Believes, with CD, that extinction may be an important factor in explaining plant distributions, but sees no reason why the several species of a genus must ever have had a common or continuous area. "Convince me of that, or show me any good grounds for it … and I think you would carry me a good way with you". It is just such people as AG that CD has to satisfy and convince.
Feels that the crossing of individuals is important in repressing variation and perhaps in perpetuating the species, but instances some plants in which it cannot, apparently, take place.
Author: | Asa Gray |
Addressee: | Charles Robert Darwin |
Date: | 7 July 1857 |
Classmark: | DAR 205.9: 381; DAR 165: 98 |
Letter no: | DCP-LETT-2120 |
From Asa Gray 16 February 1857
Summary
Discusses the ranges of alpine species in U. S. and considers the possible migration routes of such species from Europe.
Lists those U. S. genera which he considers protean and describes the U. S. character of some genera which are protean in Europe.
Describes how he distinguishes introduced and aboriginal stocks of the same species.
Author: | Asa Gray |
Addressee: | Charles Robert Darwin |
Date: | 16 Feb 1857 |
Classmark: | DAR 165: 96 |
Letter no: | DCP-LETT-2053 |