588 Species According to the Theory of Mutation. 
its simplest terms, if we call those qualities which in cross- 
ing conform to MENDEL'S law, varietal characters, and 
those which give uni-sexual unions, specific characters. 
This would conduce to a more general form of the thesis 
based on the experiments with Lychnis (p. 582), viz., 
that two related forms can differ from one another simul- 
taneously in varietal and in specific characters. 
Are they therefore to be regarded as varieties or as 
species ? Here we arrive at the boundary which separates 
facts from conventional terminology. Here lies the point 
to which GOETHE refers in his well-known lines : 
"Dich im Unendlichen zu finden, 
Musst unterscheiden nnd dann verbinden." 
The process of distinguishing is an objective one, 
that of combining subjective. The former is the imme- 
diate result of inquiry ; in our case, of systematic studies 
on the one hand, and of experiments in hybridization on 
the other. The combination is partly a question of taste ; 
it has to serve special aims ; and above all it must facilitate 
general conceptions and mutual understanding. 
It is not my task to go more deeply into the question 
of systematic subdivisions or to make any definite pro- 
posals. 1 My sole object is to place the actual facts in as 
clear a light as possible. This attempt, however, again 
leads to the conclusion that here also this insight can 
o 
only be obtained on the basis of the theory of mutation. 
It is only by attempting to analyze the species into its 
component factors, the elementary characters, that we 
1 If two forms were found to differ from one another exclusively 
in varietal characters, but the number of these were very large, they 
would probably have to be separated as species. Here also the dis- 
tinction between species and variety is an arbitrary one, and as a 
matter of fact, many of the larger groups and sometimes even whole 
families have among their distinguishing marks some which do not 
really differ from "varietal characters." 
