[E16]

Nov. 14/57/

Suppose world were to grow 10° colder. The equatorial production wd suffer most, for the inhabitants of the sub-torrid zones wd. advance of them & largely take their place & mingle - When world grew colder again; many of these might remain there the rightful original occupants having been destroyed; those which cd least will withstand greater heat retreating to their sub-torrid zones; indifferently to N. & S. - Hence I shd expect, there wd be great relation of N. & S. subtorrid zones. - As in North, these wd be from continuous land, along sub-torrid zones, may this

[over]

[E16v]

movement not explain the relation of equatorial Africa & India & Malay Archipelago. Is there not close relation in genera of warmer part of La Plata & northern temperate regions. The N. plants which are now left in warmer temperate or sub-torrid zones wd. be oddly associated & those under Equator likewise so, & wd be as much modified as the northern form on mountains of S India & Malay Archipelago - Whilst arctic forms which had kept together, wd not be modified.

[in margin:] according to [illeg]