gas WEATHERWAX: THE EVOLUTION OF MAIZE 
better. Tripsacum can be excluded from this consideration be- 
cause it depends mostly upon vegetative propagation for increase 
in number of individuals. In those grasses which have perfect 
flowers self-pollination is the rule. Tolerance of self-pollination 
may thus be interpreted as a matter of adjustment to the condi- 
tions which have prevailed during the development of the plant 
in question. 
Traumatic evolution.—Maize was one of the principal plants 
considered by Blaringhem (3, 4, 5) in arriving at his theory of 
mutation by traumatic influences, and his conclusion as to its 
evolution may best be stated in his own words (6, p. 228): 
“L’étude des variations observées A la suite de mutilations permet 
de reconstituer l’évolution du genre Zea, et d’établir que l’ancétre 
sauvage du Mais cultivé est l’espéce Euchlaena mexicana. Le 
genre Zea est une forme monstreuse du genre Euchlaena née et 
propagée par les soins de l’homme.”’_ The chief interest in his work 
in this connection lies not so much in his contribution to our 
knowledge of the evolution of the plant as in the peculiar methods 
employed and the peculiar interpretation of results. 
By mutilating plants in various ways he causes them to send 
up sprouts whose terminal inflorescences bear both male and 
female flowers. Seeds from these sprouts provide the starting 
points for numerous new varieties characterized by such peculiari- 
ties as suckers with mixed inflorescences, ears with perfect flowers, 
branched ears, tubular leaf sheaths, etc. Many of these breed 
true and are given the rank of elementary species, a number of 
new varietal names being contributed to the already overburdened 
list associated with the variations of this monotypic genus. 
Throughout the discussion, the sucker bearing a female or mixed 
inflorescence is considered an abnormality; but if this is the 
correct interpretation for the suckers of the whole genus, it con- 
stitutes a case where the exception is quite as common as the rule. 
In his description of the spikelets of the normal plant (6, p. 21) 
he states that neither the male nor the female flower contains 
organs of the opposite sex; and this fallacy becomes the basis 
for his assumption (5, p. 1253) that the acquisition of perfect 
flowers by some of his new varieties constitutes a progressive step. 
‘No change that he has produced in the plant involves any charac- 
