460 EMBRYOLOGY OF THE LOWER VERTEBRATES oh. 



Fig. 208. — PlujU,, malum 

 hypochondrialis, female 

 carrying male on her back 

 during oviposition. (After 

 Budgett, 1899..) 



retain its funnel shape. The eggs develop within the jelly up till 

 the stage oi' a tadpole of 9-10 mm. in length. 

 During this process the jelly apparently 

 liquefies, until only a thin membranous bag 

 containing watery fluid surrounds each embryo. 

 Eventually the remains of the jelly with its 

 contained tadpoles trickles downwards into the 

 water. If, as sometimes happens, the margin 

 of the water has retreated from immediately 

 below the leaf the tadpoles may still make 

 their way for a distance of several inches to 

 the pool by active jumping movements, helped 

 it may be by a shower of rain. 



In the allied Phyllomedusa sauvagii, from 

 the same neighbourhood, a similar mode of 

 oviposition occurs, though here the nest is 

 composed of several leaves (Fig. 209). Agar 

 (1909) finds in this case that both at the 

 commencement and end of oviposition there 

 are laid a large number of spheres of jelly which 



contain no egg in their interior. 1 The 



eggs are thus protected both above and 



below by a thick mass of eggless spheres. 



During the later stages of development 



the layer of envelope next the surface 



of each egg becomes greatly distended 



by the accumulation of fluid within it, 



the jelly between the eggs meanwhile 



diminishing in volume. The larvae 



with their huge external gills have thus 



considerable room in which to move 



freely. Eventually the envelope ruptures 



and the larva hatches. The nest thus 



comes to be occupied by a seething mass 



of tadpoles, floored and roofed in by a 



thick mass of jelly formed by the empty 



spheres. Eventually — in from 12-24 



hours after the bulk of the larvae have 



hatched — the jelly begins to deliquesce 



and the larvae drop down with it into 



the water. 



Similar nesting habits occur in other tropical Hylids, e.g. Phyllo- 



1 In the common Frog {liana temporaria) apparently empty capsules may be formed 

 in quantity in the oviduct before eggs begin to enter it (Wezel, 1908). Interspersed 

 with the normal eggs Agar found 2-3 per cent of such eggless capsules. These appear 

 to be deposited round small solid particles such as fragments of shed epithelium 

 (Lebrun, 1891). 



In Centrophorus, where the left ovary is no longer functional, empty tertiary 

 envelopes are frequently still formed in the left oviduct (Braus, 1906). 



Fig. 209. — Phyllomedusa sauvagii, 

 mass of spawn. (After Agar, 

 1909.) 



