426 BOTANICAL GAZETTE [DECEMBER 
SUMMARY. 
In this part of California, where conditions are locally very diverse, 
plants are more variable congenitally than in regions where the 
environment is uniform. For in the latter, natural selection acts 
along the same line on many generations, and the more closely plants 
breed true to forms fitted to their uniform environment, the better are 
their chances of perpetuation; while here natural selection is unlikely 
to work in the same way on many generations of variable plants; and 
breeding very close to a form fitted to any one sort of environment 
decreases the number of the plant’s prospective descendants. 
For the same reason, the ubiquists in this region are more variable 
than the plants of restricted occurrence. Their variation enables 
them to be ubiquists, and being ubiquists keeps them variable. 
“Mutations,” or discontinuous variations, and the most insignifi- 
cant of individual variations are parts of one unbroken series. 
GOVERNMENT LABORATORY, 
Manila, P. I. 
