274 OBITUARY x 
character of most of the productions of the 
Galapagos Archipelago, and, more especially, by 
the manner in which they differ slightly on each 
island of the group ; some of the islands appearing | 
to be very ancient in a geological sense. | | 
“Tt was evident that such facts as these, as well _ 
as many others, could only be explained on the 
supposition that species gradually become modi- 
fied; and the subject haunted me. But it was 
equally evident that neither the action of the 
surrounding conditions, nor the will of the organ- 
isms (especially in the case of plants) could account 
for the innumerable cases in which organisms of 
every kind are beautifully adapted to their habits. 
of life ; for instance, a woodpecker or a tree-frog to 
climb Biieal or a seed for dispersal by hooks or 
plumes. I had always been much struck by such 
adaptations, and until these could be explained it 
seemed to me almost useless to endeavour to prove 
by indirect evidence that species have been modi- 
fied.” (I. p. 82.) | 
The facts to which reference is here made were, 
without doubt, eminently fitted to attract the at- 
tention of a philosophical thinker ; but, until the 
relations of the existing with the extinct species and — 
of the species of the different geographical areas — 
with one another, were determined with some 
exactness, they afforded but an unsafe foundation — 
for speculation. It was not possible that this 
determination should have been effected before © 
