GENETICS: A. M. BANT A 377 
were complete and uniform — the numbers of male intergrades and apparently 
fully male individuals are few and the series is not at all diverse. On the 
other hand with the Simocephalus vetulus sex intergrade stock normal males 
are abundant and male intergrades are common in occurrence. In other 
words the sex intergrade strains of Daphnia longispina are more female and 
correspondingly less male than those of Simocephalus vetulus. 
In another manner the sex intergrades of Daphnia longispina differ from 
those of Simocephalus vetulus. Each of the several secondary sex characters 
in Daphnia longispina is subject to intermediate development and occurs in 
all intergrading stages from the fully female to the fully male secondary char- 
acter; whereas some of the secondary sex characters in Simocephalus vetulus 
are not such as to readily show so wide a range of intermediate conditions. 
One rarely finds a Daphnia longispina intergrade which has its full com- 
plement of secondary sex characters — each character apparently fully male or 
fully female. The vast majority of the Daphnia longispina intergrades have 
at least three (of a total of eight) secondary sex characters distinctly inter- 
mediate between the male and female in point of sex significance, while fre- 
quently all of the secondary sex characters partake of the intermediate 
condition. 
With the sex intergrade strains of both Simocephalus vetulus and Daphnia 
longispina the character of offspring is somewhat correlated with the secondary 
sex characters of the mother. The more maleness the female intergrade 
possesses the more highly male in general will be the character of the off- 
spring. In most cases the relative amount of maleness and femaleness pos- 
sessed by the different individuals of a brood of young is extremely variable; 
but ordinarily if the mother is highly intergrade in several characters the 
young, while quite variable will also on the average be relatively highly male 
in their characteristics. On the other hand a female from a sex intergrade 
strain who herself shows little or no evidence of maleness will ordinarily pro- 
duce young with few or slight male characters, though the young are on the 
average usually more male than the slightly intergrade mother herself. 
An extremely intergrade mother, whose secondary sex characters are all 
largely or fully male, is in most cases sterile or nearly so. This is notably true 
of the Simocephalus vetulus sex intergrades in which a female intergrade 
with a full complement of male secondary sex characters has not been known 
to reproduce. On the other hand a female intergrade with few male or only 
slightly male secondary sex characters is usually highly productive of young. 
Sex intergrade production would seem to be the result of a disturbed bal- 
ance, a condition which — obviously in many individuals and probably in all 
individuals, at least of the sex intergrade strains — is a struggle of two nearly 
equal factors or sets of factors, the one making for maleness, the other for 
femaleness. The result of this struggle of factors is individuals ostensibly 
male in part and female in part and obviously intermediate in part — but as a 
whole distinctly intermediate in sex characters. 
