532 
Colonel R. Meinertzhagen on [Ibis, 
only cases of mutational variation which I can call to mind 
in nature are dimorphic forms, and it is by no means proved 
that such are mutational. 
The mutationist will argue that whenever a domesticated 
variety resumes a wild life, the original wild stock being 
dominant to the recessive domesticated variety, such variety 
must revert, and that such a process is in strict accord with 
Mendel’s theory. 
But under natural conditions, constant variations, which 
unaided Nature has produced and which natural selection 
has perpetuated, do not revert. This still farther convinces 
me that it is dangerous to apply to wild life the results of 
evolutional experiments on domestic animals and plants. 
Both the experiments of Mendel and of more recent investi¬ 
gators have been conducted under conditions which do not 
exist in wild nature. 
I would further mention that there is no artificial mutation 
which resembles any known variation separating natural 
species one from the other. Whether we take the domestic 
pigeon, fowl, or canary, it is remarkable that no single 
artificial variety has ever, so far as we know, occurred in a 
wild state. 
I would also mention that natural selection, where environ, 
ment remains unchanged, has no effect on evolution, except 
in those few cases of dimorphism which may or may not be 
mutational. But such an exception is pure theory. 
I do, however, agree that in some cases natural selection 
may have allowed dimorphism, which is possibly mutational, 
to initiate a species. Such cases exist among the genus 
(Enanthe, in the Jackdaws (Coloeus dauricns and neglectus), 
in the Skuas, and in many others. It appears that such 
mutants might establish themselves as good species, which 
would result in two species, separated by slight superficial 
differences, inhabiting the same area. Such a state at present 
exists among the Tree-creepers, Dippers, Bock-Nuthatches, 
the Whooper ( C . cygnus ) and Bewick’s Swan (C. beivicki ), 
and others. 
But I cannot call to mind any geographical race which 
