MEMOIR. Xxxiii 
tropics of South America seem to have suffered less than the Old World. 
There are many perplexing points; temperate plants seem to have migrated 
far morethan animals. Possibly species may have been formed more rapidly 
within tropics than one would have expected. I freely confess that you have 
confounded me, but I cannot yet give up my belief that the glacial period 
did to a certain extent affect the tropics. . . . You will, I think, be glad to 
hear that I now often hear of naturalists accepting my views more or less 
fully ; but some are curiously cautious in running risk of any small cdium in 
expressing their belief. With cordial thanks and respect, believe me 
‘Yours sincerely, 
**C, DARWIN.”’ 
HT. W. Bates to Dr. F D. Hooker. 
‘KING STREET, LEICESTER, March 19th, 1861. 
‘* DEAR SIR, 
‘‘Having had the honour of an introduction to you (at the Lin. 
Soc.), I feel I am not taking a liberty in forwarding for your perusal a 
paper I have just published on the subject of the Amazonian Insect Fauna 
(the first of a series), wherein some important generalisations are introduced. 
They arise from the review of the species, and, as you will perceive, are chiefly 
on the subjects of the relations of the fauna, the variation of species, and 
especially the persistency of varieties once formed, probably by local isolation, 
after they have been brought by natural redistribution into contact with 
fellow varieties. 
‘‘T know you are one of the very few who have lately striven against 
much opposition to elevate natural history into the rank of an inductive 
science. It certainly has not been one hitherto, but merely the observation 
and cataloguing of facts. An immense multitude of curious, isolated facts, 
the significance of which has been dimly seen by their observers, have been 
accumulated; but they are unfruitful, simply because ofthe foregone and 
illogical conclusion that species are absolute and immutable. 
‘In a little paper I have written (not published), I have thought of com- 
paring natural history under these circumstances with the state of astronomy 
before Copernicus. For in the same way that all astral observations were 
barren whilst the earth was conceived to be flat, so all natural history facts 
lead to no real enlargement of knowledge whilst species are held to be 
absolutely created as they now stand. 
‘*The Ptolemean theory of revolving spheres also, I think, is quite a 
parallel case with the circular theories of Swainson, etc. 
‘**T am afraid I have done wrong in commencing to publish in a periodical 
of limited circulation. This, amongst other disadvantages, compels me to 
send copies for perusal to those who otherwise would not hear of the 
papers. 
‘‘T have accumulated a vast amount of material during my eleven years’ 
travels on the Amazons, and during the whole time directed my attention to 
the modifications of species and kindred subjects; but I have had so little 
countenance from scientific men since my return, as not to feel inclined to 
publish at all. 
c 
