72 J. M. ESSENBERG. 



and Curtis (1909), Boring and Pearl (1918) on domestic fowl, 

 and Pearl and Surface (1915) on the cow. 



An interesting case of complete sex-inversion in Tritons was 

 reported by Champy (1921). Here the inversion was from male 

 to female, which is generally considered uncommon. The Triton 

 in question was used for breeding purposes as a male. The trans- 

 formed Triton had a typical oviduct and juvenile ovary containing 

 numerous oocytes which were in the process of yolk formation. 

 Champy 's conclusion is as follows : " Ensomme nous avons chez 

 un animal adulte 1'etat ovarien d'une femalle jeune. Etant Dannee 

 1'histoire anterieure de 1'animal, il n'est pas doutex que nous 

 avons un cas d'interversion sexuelle totale." 



Frogs and toads have long been known to show peculiarities as 

 to sex conditions. Many of such abnormalities or "hermaphro- 

 dites " have been described by various observers. Lately Crew 

 (1921) has shown that all of the "abnormalities which have been 

 recorded can be so tabulated that the first case most nearly approxi- 

 mates to the normal female and the last the typical male, with 

 respect to the nature of both primary and secondary sex char- 

 acters. Thus arranged it is seen that the cases furnish an almost 

 complete series of gradations which range from an individual 

 almost completely female to one almost completely male, and that 

 the conditions found readily appear to be merely graded stages of 

 a single process." 



Witschi ('21), after a thorough investigation of the sex condi- 

 tions in frogs, concludes as follows : " Die Froshzwitter sind stets 

 genetische Ubergangsformen zwischen den reinen Geschlechtern 

 ("Qbergangshermaphroditen), und zwar geht die Entwicklung von 

 weiblichen zum mannlichen Geschlecht." 



3. Origin of Definitive Germ Cells. 



It was pointed out in the foregoing pages that in the teleost a 

 number of investigators have observed the origin of the definitive 

 germ cells from peritoneal derivatives. Such conditions have been 

 reported by Hoffmann (1886), Bohi (1904), Wallace (1904), and 

 Philippi (1908). 



Swingle (1921) reported that the lineal descendants of the pri- 

 mordial germ cells in Rana catcsbeiana degenerate. As to the 



