From J. D. Hooker [16 November 1856]1
I write only to say that I entirely appreciate your answer to my objection on the score of the comparative rarity of Northern warm-temperate forms in the Southern Hemisphere.2 You certainly have wriggled out of it by getting them more time to change, but as you must admit that the distance traversed is not so great as the Arctics have to travel & the extremes of modifying cause not so great as the Arctics undergoe, the result should be considerably modified thereby.
The Sub Arctics have 1) to travel twice as far, 2) taking twice the time, 3) undergoing manyfold more disturbing influences.—
All this you have to meet by giving the North temp. forms simply more time—I think this will hardly hold water.
Ever Yrs | Jos D Hooker Kew Sunday
JDH not happy with CD’s explanation of the absence of north temperate forms in the Southern Hemisphere, given his explanation for the spread of sub-arctic forms to the south. [CD’s note is in response to JDH’s criticism.]
Please cite as
Darwin Correspondence Project, “Letter no. 1622,” accessed on 20 January 2017, http://www.darwinproject.ac.uk/DCP-LETT-1622