102 PETER OKKELBERG 



from another species, or through overwork of the parent in repro- 

 duction, that they produce individuals of the opposite sex. Some- 

 times this sex reversal is not absolutely complete, for many of the 

 females showed different grades of masculinity in their sex be- 

 havior. Females hatched from eggs laid earlier in the season 

 were more masculine in their behavior than those of their own 

 full sisters hatched later in the season ; and a female hatched from 

 the first egg of a clutch was more masculine than her sister 

 hatched from the second egg of the clutch. Here there is, there- 

 fore, a second form of intersexualism which does not show in 

 the primary sex characters, but in the sex behavior. 



/. Sporadic hermaphroditism. Banta ('16) has published some 

 observations on the appearance of sex intergrades in the partheno- 

 genetic Phyllopod, Simocephalus vetulus. The culture was 

 started from material collected in an outdoor pond and the propa- 

 gation was continued in the laboratory. During the 131st gen- 

 eration of parthenogenetic offspring, one of the strains suddenly 

 produced a large percentage of males, together with some normal 

 females, and a large number of sex intergrades. These inter- 

 grades were either males, with one or more female secondary 

 sex characters, or females, with one to several secondary male 

 characters, together with some individuals which had hermaphro- 

 ditic sex glands and showed various combinations of male and 

 female secondary sex characters. The sex intergrades are of all 

 possible sorts of combinations of secondary and primary sex 

 characters. The highly male-like female intergrades produced 

 few or no young, and males with one or more female secondary 

 sex characters in nearly every case had incompletely developed 

 reproductive organs. 



Banta succeeded in propagating female intergrades for sixteen 

 generations with no apparent change in the ratio of the various 

 forms and with no apparent tendency of the stock to lose vigor 

 or become less prolific. An attempt has been made to classify 

 the intergrades on the basis of sex characters, and no less than 

 twenty classes are distinguished. At the ends of the scale are 

 the normal males and females. 



