THE FOUNTAIN OF CHANGE  ' 239 
it has bred true. Our knowledge of the origin of 
cultivated plants is meager, but there is considerable 
reason to believe that they began in mutations. 
We know that this was the origin of the Laciniate 
Greater Celandine, which appeared without warning 
in 1590 and has been breeding true ever since. 
Some fluctuations seem to be transmissible, and to 
reappear in varying degrees in the offspring, so that 
the possibility of man's reaching a desired end by 
persistent selection remains; but the balance of 
present-day evidence inclines to the view that the 
essential step may be taken brusquely. The 
momentous prehistoric origin of “ thrashable”’ 
wheat, for instance, may have come about abruptly 
and in one plant. Similarly, in regard to the origin 
of domesticated races of animals our knowledge is 
very unsatisfactory, but there are strong reasons for 
believing that the essential steps were due not to 
sifting fluctuations, but to breeding from transilient 
mutations. In recent years we have come to know 
of mutants arising in wild species and persisting. 
Thus the black mutant of the Peppered Moth 
has been very successful, and a similar variety of 
a certain West Indian Sugar-bird has practically 
supplanted the parent species. Now, whatever we 
may conclude as to the cause of these two novelties, 
we cannot at all events say that they were the 
results of a slow selection of individuals fluctuating 
in the direction of blackness. It is one of the 
marked changes in modern evolution-lore that 
increasing importance is being attached to mutations 
