1x THE DEBT OF SCIENCE TO DARWIN 453 
species that now exists or ever has existed on the globe was 
known to involve difficulties and contradictions of the most 
serious nature, although it was seen that many of the facts 
revealed by comparative anatomy, by embryology, by geo- 
graphical distribution, and by geological succession were 
utterly unmeaning and even misleading, in view of it; yet, 
down to the period we have named, it may be fairly stated 
that nine-tenths of the students of nature unhesitatingly 
accepted it as literally true, while the other tenth, though 
hesitating as to the actual independent creation, were none 
the less decided in rejecting utterly and scornfully the views 
elaborated by Lamarck, by Geoffroy St. Hilaire, and at a 
much later date by the anonymous author of the Vestiges of 
Creation—that every living thing had been produced by some 
modification of ordinary generation from parents more or less 
closely resembling it. Holding such views of the absolute 
independence of each species, it almost necessarily followed 
that the only aspect of nature of which we could hope to 
acquire complete and satisfactory knowledge was that which 
regarded the species itself. This we could describe in the 
minutest detail; we could determine its range in space and 
in time; we could investigate its embryology from the 
rudimental germ, or even from the primitive cell, up to the 
perfect animal or plant; we could learn every point in its 
internal structure, and we might hope, by patient research 
and experiment, to comprehend the use, function, and mode 
of action of every tissue and fibre, and ultimately of each 
cell and organic unit. All this was real knowledge, was solid 
fact. But, so soon as we attempted to find out the relations 
of distinct species to each other, we embarked on a sea of 
speculation. We could, indeed, state how one species differed 
from another species in every particular of which we had 
Imowledge ; but we could draw no sound inferences as to the 
reason or cause of such differences or resemblances, except by 
claiming to know the very object and meaning of the creator 
in producing such diversity. And, in point of fact, the chief 
inference that was drawn is now proved to be erroneous. It 
was generally assumed, as almost self-evident, that the 
ultimate cause of the differences in the forms, structures, and 
habits of the organic productions of different countries, was 
