No. 381.] THE CONCEPTION OF SPECIES. 679 
felt that a new day had dawned; that the old view of looking 
at species as fixed creations, and ignoring as far as possible the 
significance of their tendency to vary, had been forever upset 
by Darwin, and that hereafter we must look to evolution as 
brought about by natural selection to interpret species as we 
_now find them. Not being well informed in regard to the his- 
tory of scientific opinion, we assumed somewhat hastily that 
before Darwin all was darkness, and we did not trouble ourselves 
to go back and inquire whether there were not others who had 
had at least glimpses of the great truths of evolution; but even 
had we heard that there were some before Darwin who did not 
believe in the fixity of species, it would still have been true 
that it was Darwin’s book by which, practically, the world at 
large was enlightened on the subject. 
Forty years have passed, and inasmuch as we are all evolu- 
tionists, either of the Darwin school or some related school, the 
question suggests itself, Is our belief in evolution merely dog- 
matic, like some of the theological doctrines which we believe 
thoroughly but which we do not allow to interfere with our 
daily life, or, as far as botany is concerned, has our belief modi- 
fied the manner in which we treat what we call species? The 
mere fact that we now recognize that species have been derived 
from other species, and are on the way to develop into still other 
Species, would naturally lead us to be more liberal in our treat- 
ment of them systematically than inthe days when variation 
was almost a crime against the Almighty. Certainly, with 
evolution as a key to guide us, our conceptions of genera and 
orders ought to be far more scientific than they were. 
A species has been defined as a perennial succession of like 
individuals; and, although no definition is perfect, I doubt 
whether a better definition of species has ever been invented. 
It isa peculiarity of definitions, however, that they all need to 
be defined. In the present case we must be told what is meant 
by the word perennial, and what is meant by like. To the pre- 
Darwinian, perennial, of course, meant for all time. By the 
early Darwinians we are not told whether by perennial they 
meant a hundred, a thousand, or a million years ; but until at 
least we know approximately what is meant, we must still ask 
