There must have, I should think, existed some curious barrier on American High-Road: dryness of Peru, excessive damp of Panama, or some other confounded cause, which either prevented immigration or has since destroyed them.
You say I may ask questions, and so I have on enclosed paper; but it will of course be a very different thing whether you will think them worth labour of answering.
May I keep the lists now returned?
otherwise I will have them copied.
You said that you would give me a few cases of Australian forms and identical species going north by Malay Archipelago mountains to Philippines and Japan; but if these are given in your "Introduction" this will suffice for me.

(340/3.

See Hooker's "Introductory Essay," page l.) Your lists seem to me wonderfully interesting.
According to my theoretical notions, I am not satisfied with what you say about local plants in S.W.corner of Australia (340/4.

Sir Joseph replied in an undated letter: "Thanks for your hint.

I shall be very cautious how I mention any connection between the varied flora and poor soil of S.W.