292 Evolution and Adaptation 
relatives, not in one character only, but in nearly all their 
characters. There is no ground, De Vries states, for believ- 
ing them to be varieties. If it is found inconvenient to rank 
them under the names of the old Linnzan species, it will be 
better, perhaps, to treat them as subspecies, but De Vries 
prefers to call them elementary species. 
In regard to the distribution of species in nature, it may be 
generally stated that the larger the geographical domain so 
much the larger is the number of elementary species. They 
are found to be heaped up in the centre of their area of dis- 
tribution, but are more scattered at the periphery. 
In any one locality each Linnzean species has as a rule 
only one or a few elementary species. The larger the area 
the more numerous the forms. From France alone Jordan 
had brought together in his garden 50 elementary species of 
Draba verna. From England, Italy, and Austria there could 
be added 150 more. This polymorphism is, De Vries thinks, 
a general phenomenon, although the number of forms is sel- 
dom so great as in this case. 
Amongst animals this great variety of forms is not often 
met with, yet amongst the mammalia and birds of North 
America there are many cases of local forms or races, some 
of which at least are probably mutations. This can only be 
proven, however, by actually transferring the forms to new 
localities in order to find out if they retain their original char- 
acters, or become changed into another form. It seems not 
improbable that many of the forms are not the outcome of 
the external conditions under which the animal now lives, 
but would perpetuate themselves in a new environment. 
From the evidence that his results have given, De Vries 
believes it is probable that mutation has occurred in all direc- 
tions. In the same way that Darwin supposed that individ- 
ual or fluctuating variations are scattering, so also De Vries 
believes that the new forms that arise through mutation are 
scattering. On this point it seems to me that De Vries may 
