JORDAN’S SPECIES 9 
It has already been pointed out that Linnzus him- 
self distinctly deprecated this process of splitting. 
‘Varietates levissimas non curat botanicus,’ said 
Linneus. Jordan, however, applied the method of 
experiment to many of the species of his own defini- 
tion, and having transplanted them from a variety 
of localities to the uniform soil of a garden, found that 
they preserved their distinctive characters and came 
perfectly true to seed. 
It appears then that Jordan’s species are just such 
true and constant groups as those of Linneus. They 
are separated from one another by definite features of 
form and structure, only these differences are not so 
wide as those which separate Linnzan species. The 
latter are, indeed, to be looked upon as more or less 
artificial groups or aggregates of these physiological 
species, as Jordan’s species have also been called. The 
problem of the origin of the smaller groups is clearly 
to be placed before that of the origin of the larger 
species. 
It is true that in the case of certain groups of 
animals and plants there would appear to be no possi- 
bility of drawing hard and fast lines between the 
species, which thus seem to shade gradually one into 
the other. There is, however, a great difference 
between the admission that certain nearly related 
species are difficult or impossible to separate definitely, 
and the statement that there is no true distinction 
between them, and the latter statement is one which 
few are bold enough to make. The case stands thus. 
We know that great numbers of large groups (classes 
