260 Brown: THE GENUS CRATAEGUS 
Some of the points just made may be taken as evidence of mu- 
tations, but the best known mutants are not as irregular in char- 
acters as many of the species of Cvataegus. Cultures carried 
through several generations are necessary in order to test whether 
or not Crataegus species throw off mutants. 
I am greatly indebted to the gentlemen mentioned for their 
kindness in answering my questions, and to W. W. Eggleston, 
especially for data concerning the number of species attributable 
to the different authors. 
CORNELL UNIVERSITY, 
ITHACA, NEw YORK 
