590 Species According to the Theory of Mutation. 
sa maniere de voir, tine association de formes voisines." 1 
On the other hand JORDAN, as is well known, based his 
conception of the smaller or elementary species as the 
real species on the same fundamental proposition. The 
wish to see in the species something real, has always 
played a prominent part ; but the reality as it appeared 
to the descriptive biologist has been very different from 
that in the mind of the experimental investigator. 
It would certainly be desirable to agree to call only 
one of the two groups species ; it is only the question 
which. The older view and the popular idea limit this 
term to the larger groups, and give the name of sub- 
species to the smaller ones. 2 But the term subspecies, 
as it is now in use does not signify a unit, but a group 
of units which is also compound and merely differs from 
the species itself in being smaller (Part I, p. 60). The 
modern tendency is to regard the smaller types as spe- 
cies, and wherever the criterion is of an experimental 
kind, like that employed by JORDAN, tin's view will pre- 
dominate. Its importance to descriptive biology has re- 
cently been demonstrated in a most clear and convincing 
manner by BELLI : 3 and there seems every prospect of its 
being recognized by the best systematists. 
It has been proposed to denote collective species by 
a special name, and the word "stirp" has been suggested. 
This term has been applied in this sense by several sys- 
tematists. 4 and BELLI has adduced a long series of histor- 
1 ALPH. DE CANDOLLE, Arch fa. dcs sc. dc la bib!, unfacrscllc, Ge- 
neva, Febr. 1878, Vol. LXI, p. 4. 
2 In what follows, I shall leave varieties, in the sense in which 
this term has been used in the foregoing sections, out of account. 
3 S. BELLI, he. at. 
4 For instance, H. LEVETLLE, Monographic dn genre Ocnothcra, 
1902. T, pp. 72, 106, etc. 
