II 



SrKRMA-F.CUJS 



53 



Fig. 8. — A liell-sliaped 

 spermatopliore of 

 Triton (iljiesfris. x 3. 

 (After Zeller.) i 



fecundation of the female without actual copulation. The fenuile 

 takes up smh a deposited spermatopliore with the cloacal lips, 

 squeezes the sperma out of the capsule whicli remains 1)ehin(l, and 

 eitlier conveys the former into a special receptaculum seminis, 

 e.g. in Salamandra atra and in Triton, or the spermatozoa wriggle 

 tlieir way, thanks to the luululating tail, directly up the oviducts 

 to tlie ova. 



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

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

 The shell of jelly is in fact a cast of the 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 Triton. Those of Salamandra maculosa 

 are much simpler, consisting, in conformity 

 with the absence of a cloacal papilla, merely of 

 a cone with a globular mass of sperma on the 

 top. Those of Amhlystoma are similar. 



The spermatozoa of the Anura show con- 

 siderable differences in the various genera, of 

 which, however, only the European forms have been properly 

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

 Pdohates, and Pelodytes ; spindle-shaped, more or less curved, in 

 Rana temjwraria and B. agilis, Hyla, Bufo and Bomlnnator, in 

 the latter with an irregular membrane on one side ; cyliiulrical 

 in Rana csculenta and R. arvalis. The tail is mostly long and 

 tiliform, but in Biifo vulgaris and Biscoglossus it is provided with 

 an undulating membrane. Their size is generally very small, 

 only about O'l mm., excepting those of Biscoglossus which reach 

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

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

 genus, e.g. Rfoia temporaria and R. arcalis, cannot fertilise eacli 

 other. 



'I'iie eggs differ much in size, colour, and numbers. They 

 are iiuloljlastic, with miequal cleavage, but those species which 

 possess an unusual amount of food-yolk, for instance R/iaco2Jhorus 

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

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

 is the number of eggs ]>roilnced. But the number which is laid 

 ' Zritsehr. iviss. Zoo/, xlix. 1889, p. 58:3. 



