154 
Psyche 
[December 
two X-chromosomes, the male by one. The loss of one X-chro- 
mosome by non-disjunction or in any other manner would 
presumably recult in maleness. If the loss occurred before the 
first somatic division, the entire individual would be male,— if it 
occurred later a gynandromorph would presumably result. In 
the gynandromorph mentioned, the left side throughout the 
entire length was typically typically female, the right side was 
male, suggesting that the loss of an X-chromosome had occurred 
at the first somatic division. 
One of the males was placed in a cage with several females 
which had just attained sexual maturity. Only females appeared 
in their progenies. Copulation was not observed, but the, insects 
were seldom examined at night. Nachsheim mated one of the 
males which appeared in his cultures with females and observed 
repeated copulation but with no effect upon the sex of the pro- 
geny, — as in the progenies resulting from unmated individuals, 
all were females. Since, according to Pehani (1924) normal sper- 
matozoa were produced by one of the sporadic males studied by 
him, it appears that the eggs have lost their capacity for fer- 
tilization. 
In forms whose eggs have the ability to develop partheno- 
genetically and where parthenogenetic reproduction results 
exclusively in females, a trend in the sex ratio is automatically 
set up, which must end in the ultimate elimination of males 
unless this effect is offset by some factor or factors such as 
greater viability of males or of male-producing spermatozoa, 
which tend to distort the sex ratio in the opposite direction. In 
the Orthoptera, forms having the capacity for parthenogenetic 
reproduction are known in which males are never found, others 
in which males are rare, and still others in which the sex ratio is 
near equality. It must be concluded that forms in the last 
category have developed the capacity for parthenogenesis only 
recently or, as already suggested, that the trend toward an excess 
of females, which would otherwise be an inevitable concommitant 
of thelyotokous parthenogenesis, is being offset by other factors 
tending toward an excess of males. 
