64 The Different Modes of Origin of new Species. 
a. but with ft and are therefore considered as having been 
derived from a Forma typica or gcnuina and not as being 
of equal value with this. Evidently the principle on 
which they are classified is borrowed from a consideration 
of horticultural varieties. This proceeding, however, is 
only justified in the relatively rare cases in which horti- 
cultural varieties can be demonstrated to be younger than 
the species. Besides this the geographical distribution 
of the forms in question is often employed to decide 
which is the species, and which are the varieties. If one 
particular form is wide-spread and another only local 
or sporadic in its appearance it is obvious that the former 
will be regarded as the older and therefore as the species. 
Often this fits in conveniently with the fact that the 
species was discovered earlier than the variety, so that 
instead of disturbing the classification in the system all 
that had to be done was to range the variety under the 
species. 
The exigencies of space prevent me from going into 
further detail here. What I have already said may suffice 
to show that the systematic term "variety" means two 
fundamentally different things to LINNAEUS and the 
later systematists : 
1. Homonomous Forms, amongst which even LIN- 
NAEUS could not select one as a type for the others ; 
"Elements de 1'espece" (DE CANDOLLE) or ele- 
mentary species. 
2. Derived Forms, which are distinguished from the 
type of the species only by the decreased or in- 
creased development of a particular quality; or 
by its complete absence: True varieties. 1 
Amongst these, again, the simple invariable types are to be 
distinguished from the intermediate or eversporting races. (See 
3-4-) 
