HERMAPHRODITISM IN EURYCEA BISLINEATA. 351 



velopment of eyelids and naso-labial groove (advanced 

 phase). 



The specimens used constituted representative collections made 

 through a period of several years and had been preserved either in 

 alcohol after fixation in Bouin's solution, or in formalin. 



The method followed in sexing was first to examine the gonads 

 in situ under a Bausch and Lomb binocular dissecting microscope 

 with a strong artificial illumination. In many cases this was suf- 

 ficient to diagnose the sex, but in those cases in which it was not, 

 the gonad was removed and cleared in toto in glycerine for more 

 careful study under the compound microscope. If in sexing one 

 begins with adults and continues through the smaller and earlier 

 stages, one comes finally to a point where it is practically impos- 

 sible to be sure of the sex. Individuals of less than 27 mm., 

 though frequently possessing readily sexed gonads, more often ex- 

 hibit a developmental condition which might admit of various 

 interpretations, since, at least without the use of cytological cri- 

 teria, the small cells present might be either oogonia or spermato- 

 gonia. Bouin ('01) found that in Rana temporaria the first de- 

 velopment of male and female germ-cells is identical as far as 

 origin and general appearance are concerned. It may even be the 

 case in Eurycea, as Okkelberg ('21) has shown for the brook 

 lamprey, that the animal passes through a period of sex indif- 

 ference before sex differentiation sets in. His observations " seem 

 to warrant the conclusion that each larva of this species (Entos- 

 phcnus wilder-i) carries the potentiality of both sexes and that sex, 

 therefore, is not irrevocably fixed at fertilization." He explains 

 the development of sex in these gonads of ' potentially either ' : 

 sex by showing the presence in the gland of two kinds of germ 

 cells, those manifesting a tendency towards rapid division (kata- 

 bolic) and those showing a tendency to growth (anabolic). He 

 says : " The former are regarded as having a male and the latter a 

 female potentiality. The relative proportion of anabolic and kata- 

 bolic cells determines whether the larva becomes a male or a 

 female individual." 



Since our problem, however, was not one dealing with a possible 

 early transitory hermaphroditic condition, we have included in 

 the calculation of the percentage of occurrence only those indi- 



