SCHAFFNER: SEX REVERSAL IN THE JAPANESE HOP = 75 
time but finally developed a lower branch with a mixed inflores- 
cence, several flowers showing imperfect ovularies and a number 
of well-developed stigmas. It is evident then, that reversal of 
sex varies both in the extent of the tissues involved and in the 
intensity or perfection of the given state. A large carpellate 
plant may produce but one imperfect stamen during its entire 
ontogeny and a staminate plant may show no sex reversal 
except the development of a single stigma on the entire individual. 
At the other extreme both kinds of individuals may produce 
perfect structures of the opposite sex. Some individuals show 
such a decided bisporangiateness that they sometimes have 
nearly equal numbers of the two kinds of structures in various 
degrees of perfection. 
In hemp the general tendency appears in age to be towards 
maleness in both staminate and carpellate plants, altho some 
individuals are exceptional in this respect; but such a tendency 
was not evident to any extent in the Japanese hop except in a 
few individuals. The important factor in causing the reversal 
of the sexual state in the winter plants seems to be the greatly 
shortened period of daily illumination, and from other experi- 
ments it is probable that reversal takes place more readily if 
the plants are at the same time growing in a very rich soil, 
largely made up of well-rotted cow manure. 
The nine carpellate plants which showed no reversal remained 
in the greenhouse until May when they were showing a decided 
rejuvenation and were planted out of doors where they continued 
to be pure carpellate. 
The same kind of sex reversal was obtained in the winter of 
1921-22, but the press of other experiments prevented a detailed 
study. No less remarkable than the reversal of the sexual 
state shown by the winter plants are the decided shortening of 
the vegetative period before anthesis and the great reduction 
in the size of the plant body. One extreme staminate inter- 
mediate plant had two cotyledons and two pairs of leaves and 
then ended in a small terminal inflorescence. There were flower 
clusters also in the axils of the cotyledons and the four leaves. 
The accompanying plate represents a series of flowers to 
show in a general way the progressive change of sexual expression 
and the confusion which sometimes occurs in the stamens and 
ovularies. The examples, however, do not by any means 
