I 
WHAT AKE SPECIES 
7 
several peculiarities of habit and of geographical distribution 
might have been brought about—whether, if this were done, 
the “origin of species ” would be discovered, the great 
mystery solved, he would undoubtedly have replied in the 
affirmative. He would probably have added that he never 
expected any such marvellous discovery to be made in 
his lifetime. But so much as this assuredly Mr. Darwin has 
done, not only in the opinion of his disciples and admirers, 
but by the admissions of those who doubt the completeness 
of his explanations. For almost all their objections and 
difficulties apply to those larger differences which separate 
genera, families, and orders from each other, not to those which 
separate one species from the species to which it is most nearly 
allied, and from the remaining species of the same genus. They 
adduce such difficulties as the first development of the eye, or 
of the milk-producing glands of the mammalia ; the wonderful 
instincts of bees and of ants; the complex arrangements for 
the fertilisation of orchids, and numerous other points of 
structure or habit, as not being satisfactorily explained. But 
it is evident that these peculiarities had their origin at a very 
remote period of the earth’s history, and no theory, however 
complete, can do more than afford a probable conjecture as to 
how they were produced. Our ignorance of the state of the 
earth’s surface and of the conditions of life at those remote 
periods is very great; thousands of animals and plants must 
have existed of which we have no record; while we are 
usually without any information as to the habits and general 
life history even of those of which we possess some fragmentary 
remains ; so that the truest and most complete theory would 
not enable us to solve all the difficult problems which the 
whole course of the development of life upon our globe 
presents to us. 
What we may expect a true theory to do is to enable us 
to comprehend and follow out in some detail those changes in 
the form, structure, and relations of animals and plants which 
are effected in short periods of time, geologically speaking, 
and which are now going on around us. We may expect it 
to explain satisfactorily most of the lesser and superficial 
differences which distinguish one species from another. We 
may expect it to throw light on the mutual relations of the 
