SPERMA-EGGS 5 3 



fecundation of the female without actual copulation. The female 

 takes up such a deposited spermatophore with the cloacal li]»s, 

 squeezes the sperma out of the capsule which remains liehind, and 

 either conveys the former into a special receptaculum seminis, 

 e.g. in S'a/nviandra atra and in Triton, or the spermatozoa wriggle 

 their way, thanks to the undulating tail, directly up the oviducts 

 to the ova. 



The spermatophores are composed of a colourless, soft, gela- 

 tinous mass, which is probaltly produced by the cloacal gland. 

 The shell of jelly is in fact a cast of tlie cloacal 

 cavity, reproducing all its ridges, furrows and 

 folds, while a toad -stool -shaped papilla of 

 the cloaca makes the inside lumen of the cast, 

 e.g. in Trito'n. Those of HalamandrK riKicnlosa 

 are much simpler, consisting, in confcn-mity 

 with the absence (jf a cloacal papilla, merely <jf 

 a cone with a gloliular mass of sperma on the 



,n, P . ,, • -1 Fm. 8.— A hell-.shai.uil 



top. ifiose 01 Anih/i/sfoma are similar. spermatophore of 



The spermatozoa of the Annra sliow con- TriJ^>» a/jjestris. x s. 



^ , . . (After Zeller.) ' 



siderable differences in the various genera, of 

 wliich, however, only the European forms have Ijeen properly 

 examined. Tlie " head " is wound like a corkscrew in Discoglossvs, 

 Prfohafes, and Pchxhjffs ; spindle-sliaped, more or less curved, in 

 Band temiKyvdvUi iind R. ngilix, Hyla, Bufo and Bomhinator, in 

 the latter with an irregular membrane on one side ; cylindrical 

 in Band cscidenta and B. (irralis. The tail is mostly long and 

 filiform, but in Bufo vulgaris and Discoglossns it is ])rovided with 

 an undulating membrane. Tlieir size is generally very small, 

 only aV)out O'l mm., excepting those of Discog/ossv.s which reach 

 tlie astonishing length of 3 mm. These differences in shape, 

 especially that of the head, explain why species of the same 

 genus, e.g. Baiia trm^wrariff and B. m-nflis, cannot fertilise each 

 other. 



The eggs differ much in size, colour, and numbers. They 

 are hololjlastic, with unequal cleavage, but those species whicli 

 possess an unusual amount of food-yolk, for instance Bhacophorus 

 schlegeli and the Apoda, approacli the meroblastic type of segmen- 

 tation. As a rule, the greater the amount of yolk, the smaller 

 is the nunil)er of eggs produced. But the number which is laid 

 ^ Zi'.itschr. wiss. ZooJ. xlix. 1889, p. 583. 



