MEMOIR. Ivii 
‘Your instance of the woolly sheep hits me hard ; itis the very fact of this 
undoubted influence of conditions over zzdumentum that puzzles me above 
all others. It is inconceivable at first sight that a sheep, however woolly 
when transported to a climate which causes all wool to vanish, should have a 
breed of lambs as well woolled as those of a cold climate, but it is possible. 
I quite understand the climate bringing on a change in the skin of the indi- 
vidual sheep, and influencing growth of hair, which is only an appendage of 
the skin ; but I find it hard to believe that this change wrought on individuals 
should be directly propagated. Lop-eared rabbits are, I think, pure cases of 
artificial selection ; of dogs I know not, but should suspect it too, as we have 
thousands of breeds of prick-eared dogs who do not want their ears more than 
the lop-eared do. 
**T do not think I have anywhere published any notices of colours of plants 
in relation to climate, but I will see and let you know. I think I have some- 
where noticed woolly plants not being more arctic than tropical, and will hunt 
up reference. 
‘‘One more point in connection with disuse of organ. In all these cases 
the loss of an organ must be counterbalanced by increased activity of other 
or others, and the #azerza/ used for lost organ is diverted to others; so here 
natural selection comes doubly into play, not only selecting individuals in 
which the disused organs are small, but those in which the szaZerial goes in 
a desired direction. 
‘* Fleshiness of plants on sea coast is a case I am disposed to attribute to 
direct influence of conditions ; wet and succulence go together so naturally 
that it is difficult to conceive of these not being cause and effect, and we have 
it displayed in every way everywhere. But then, fatness of general tissues, like 
large leaves, flowers, fruit, etc., etc., hardly come under same category as 
variation of form, etc., though it is hard (impossible?) to separate them 
philosophically. 
‘With regard to colour of negro being ‘ due to direct action, and also being 
best suited to climate,’ do not forget that the Tasmanian was awfully black, 
ditto the Fuegian, and the New Zealanders and Eskimaux both very dark. It 
has always struck me as odd that man is the only animal that blackens in 
tropics ; if this was an affair of direct action of sun, why are no other animals 
black in tropics ? 
‘* Ever yours, 
** Fx DS HOOKER.” 
Hl. W. Bates to Dr. J. D. Hooker. 
‘““ KING STREET, LEICESTER, March 21st, 1862. 
**MY DEAR SIR, 
‘* Many thanks for the trouble you have taken in determining the 
nature of the clothing on the underside of the leaves sent. It is a pity I did 
not get the flower or fruit of the tree. 
** All the leaves of the tree did not possess the wool. Is it to be considered 
an excretion of the leaves or natural clothing of them, or a foreign substance ? 
‘* Please keep the box until next journey to town. 
*‘T think I said in my last that I had not finished answering your very 
important letter. In fact mine was not a close answer to it at all, which you 
