336 



sides, the great development and full differentiation of the oviduct 

 of the left side would certainly seem to be associated with the great 

 relative size of the ovarian portion of the genital gland. 



Comparison of Bourne's and Maeshall's specimens would how- 

 ever appear to negative the deduction no less forcibly, for if it be te- 

 nable, the great development of the oviduct recorded by the latter*^) 

 is irreconcilable with the insignificance of the Bidder's organ. Neither 

 Marshall nor Sutton give the ages of their specimens; that my 

 own is a very young one is certain, and that that of Marshall just 

 referred to was an old one appears tolerably clear. 



It is obvious that the progressive development of the Miillerian 

 duct is not an invariable accompaniment of the formation of a Bidder's 

 organ. On careful comparison of the several descriptions and figures 

 I think it not improbable that the organ of Bidder may undergo, 

 in the common Frog, a gradual reduction with advancing age, such 

 as Knappe has observed') in the female of Bufo. If so, the obser- 

 vations of Marshall and Sutton would not appear to be conflicting, 

 and the generalization of the latter might conceivably hold good for 

 those individuals in which the oviduct is represented. 



Knappe has shewn (p. 499) that in Bufo vulgaris the Bidder's 

 organ undergoes an annual reduction during hibernation and a corre- 

 sponding regeneration during summer. He further suggests (p. 547) 

 that the corpus adiposum (which he holds with Spengel, in contra- 

 distinction to V. WrrTiCH and Marshall is not a fatty degenerate 

 germinal blastema) is simply a "Reserven ah rungs behält er". 

 Direct experimental investigations upon the physiology of this organ 

 are the more desirable seeing that Cope has recorded ^) the exi- 

 stence in H e m i s u s of an "external corpus adiposum which 



lies between the strata of the external and internal oblique muscles, 

 along the anterior margin of the lobe of the liver, on each side". 



6) 1. c. pi. 6. fig. 1. 



7) On the families of the Raniform Anura. Journ. Acad. Nat. Sei. 

 Philadelphia., Vol. 6 (1866—1869), p. 199. 



8) 1. c. p. 498. 



April 5, 1888. 



