458 KING. [Vou. XIX. 
workers and it is probable, as Knappe suggests, that Muller 
mistook tadpoles of Bufo for those of other species of am- 
phibians. Knappe found a Bidder’s organ in a young male 
Salamandra about two years old, but he gives no details of 
its structure. As far as I have been able to determine, these 
are the only recorded cases in which a Bidder’s organ has 
been found in amphibians other than the Bufonidae. The 
numerous cases of hermaphroditism that have been reported 
in different species of Rana and the investigations of Pfluger 
(25) which show that large numbers of tadpoles of Rana 
temporaria are hermaphroditic would seem to indicate that 
a body somewhat of the nature of the Bidder’s organ in Bufo 
is not infrequently formed in Rana. I am at present investi- 
gating the development of the germ-cells in a number of 
species of American amphibians, and I hope later to record my 
observations regarding the presence or absence of Bidder’s 
organ in these forms. 
Bidder’s organ has been a subject of controversy ever since 
its discovery in 1758 by Rosel von Rosenhof (27), and a 
number of different theories have been advanced regarding 
its nature and probable function. The discoverer of this organ 
considered it a part of the fat body, while Ratke (28), who 
examined it in 1825, believed it to be a portion of the testis. 
Three years later Jacobson (15) came to the conclusion that 
all toads are hermaphrodites since the body at the anterior end 
of the testis is a rudimentary ovary. This view was adopted 
in 1853 by von Wittich (34), after a study of Bidder’s organ 
in Bufo cinereus, and it has since been advocated by La 
Valette St. George (29), Nussbaum (23), Bourne (3), Cer- 
ruti (6) and Ognew. Hoffman (14) believes that Bidder’s 
organ contains both ova and spermatozoa, and he therefore 
considers that this body is a “rudimentare Zwitterdrtise.” On 
the other hand, Bidder (1) maintains that the body at the 
anterior end of the testis is not a rudimentary ovary but an 
“Abtheilung des Hoden, und zwar eine auf einer niedrigen 
Entwickelungsstufe stehen gebliebene, welche die Bildung des 
Sperma und der Spermatozoen nun vorbereitet.” Leydig (19) 
