XXXI 
THE FOUNTAIN OF CHANGE 
NE of the fundamental problems of Biology 
is the origin of the distinctively new. A 
clever and well-proportioned dwarf is born in a 
family, and the interesting type may reappear in 
a certain proportion of his descendants for at least 
four generations. The unsolved problem is: What 
conditioned the dwarf? It is the same problem 
as the origin of the mathematical or the musical 
genius, the old problem of new departures, It is 
difficult to draw the line, but it seems possible to 
discriminate between minor novelties or “ fluctua- 
tions,” which differ but slightly from the parent 
type or may be connected with it by intermediate 
gradations, and the major novelties or ‘‘ mutations ” 
which represent more or less of a new pattern and 
are discontinuous. The contrast is not so much 
in the amount as in the kind of change. The 
copper beech, which made its appearance in the 
seventeenth century, may not differ very materially 
from an ordinary beech, but it was a discontinuous 
variant which arose abruptly and came to stay. 
Similarly, the white rat does not seem to want very 
much to make it a brown rat—the species whence it 
sprang—but it was in its day a new departure, and 
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