IX.] THE COMMON FROG. 147 



animals just mentioned, when fully adult, unlike all 

 higher animals, have no separate duct in the male 

 analogous to the oviduct of the female. There is but 

 a single tubular canal, and into it directly open minute 

 tubes, which proceed both from the renal, or urinary, 

 gland and from that which is the analogue of (and is 

 complementary to) the ovary. 



The interest of these conditions is twofold. In the 

 first place, their existence is a point of affinity with 

 fishes, since we find in those belonging to the order 

 to which Lepidosiren and Ceratodus pertain, a similar 

 connection between the same two sets of organs. 



It is interesting, in the second place, because, though 

 nothing of the kind exists in adult animals of a higher 

 class than Batrachians, yet, as already stated, in the 

 earlier stages in the development of such animals 

 (even the very highest) we do find a certain analogy. 



The primitive urinary gland — the Wolffian body — 

 seems then to answer to the permanent urinary gland 

 of Batrachians. This, together with its duct, is at 

 first, indeed, entirely devoted to the excretory func- 

 tion. But, as we have seen, it ultimately more or less 

 aborts in the adults of both sexes, and becomes an 

 appendage, exclusively, of parts which are relatea 

 directly or indirectly to oviposition. 



L 2 



