


LOTSY, CURRENT THEORIES OF EVOLUTION. 413 
Yet, DARWIN does not consider them as such, because (p. 18) 
„hardly any cases have been ascertained with certainty of hybrids 
from two quite distinct species of animals being perfectly fertile”, 
while the hybrids between all the breeds of the pigeon are per- 
- fectly fertile. 
I fancy that it is this very reason which prevents BATESON from 
accepting the evidence of any form obtained artificially as con- 
clusive, in the question of the origin of species; that he also con- 
siders mutual sterility as the character par excellence of the species. 
This view seems to me untenable; the number of species which 
produce fertile hybrids is increasing daily, while on the other hand 
we know of self-sterile plants, whose pollen and eggcells should, 
if sterility of a cross were a sure indication of specific difference, 
be considered as specifically distinct. 
It seems to me that the belief that species should be sterile with 
One another is nothing but a survival of the idea that species have 
been separately created and therefore should not interbreed. 
To my way of thinking, the species-concept has ceased to exist 
Since it was proved that evolution had taken place. 
Inherent to the species-concept is the doctrine of its immutability, 
the doctrine that all ancestors of a particular type have been of 
that very type thémselves. 
Since this view was proved to be untenable the species-concept 
should have been abandoned. 
The Linnean species, to which BATESON refers, is no element of 
descent, it is simply a group of morphologically similar, not of 
genotypically identical, individuals and may be, and in many cases 
doubtless is, polyphyletic in origin. 
We do not find species in nature, what we observe there are 
different individuals, not different species. Some of these habitually 
interbreed, form a pairing community or syngameon and it are 
these syngameons which we, erroneously, designate as species. 
Within these syngameons a certain number of different kinds of 
chromosomes (certainly greater than the chromosome number 
characteristic of that syngameon, just as in a house a large number 
of different kinds of chairs may be present, even if in each room 
of that house say only four chairs are placed) are present, and their 
different combinations, or in the tase of crossing-over, the different 
