No. 381.] THE CONCEPTION OF SPECIES. 693 
its publication, in 1821-32, his Systema Mycologicum was 
certainly a masterpiece. If the species described by him in 
genera, such as Spheeria, for example, which were then con- 
sidered valid, are no longer recognized as such, it is not because 
in limiting his species as he did Fries did not employ with 
remarkable skill the same scientific principles of classification 
as the mycologists of to-day, but mainly because the modern 
application of the microscope to the study of the spores and 
some other characters has brought out facts unknown at the 
beginning of the century. The species of Fries have been 
split up and changed in many respects, and while we feel sure 
that the modern classification, thanks to improved micro- 
scopes, is an improvement on his, who shall dare say that 
hereafter some present unknown and unsuspected method of 
analysis may not furnish facts which will overturn our present 
system ? 
I should feel that I ought to apologize for bringing up a sub- 
ject so very, very threadbare, were it not that some botanists 
shrink from acknowledging the fact that what we botanists call 
species are really arbitrary and artificial creations to aid us 
in classifying certain facts which have been accumulated in 
the course of time, and nothing more. So long as we enter- 
tain even a lingering suspicion that they are anything more, 
systematic botany will not be able to accomplish its real object, 
which is certainly very important. We are all convinced, 
theoretically at least, that not only are all plants gradually 
changing, and sooner or later will no more be what they now 
appear to us to be than they are now what they were in 
times past, and we also know that the means which we have 
of studying them are changing as well. Our so-called species 
are merely snapshots at the procession of nature as it passes 
along before us. The picture may be clear or obscure, natural 
or distorted, according to our skill and care, but in any case it 
represents but a temporary phase, and in a short time will no 
longer be a faithful picture of what really lies before us; for 
we must not forget that the procession is moving constantly 
onward, and at a more rapid rate than some suspect. Better 
cameras will be invented, and when another generation of bota- 
