CONCERNING TADPOLES 193 



not surrounded by a layer of black pigment ; and this 

 because they are excluded from the sun's rays and hence 

 the pigment, which serves at once as a screen from ex- 

 cessive light, and to attract heat, is useless. 



The '■ Wollunnkukk " {Phyllomedusa hyfochondrialis) of 

 Paraguay furnishes an even more extraordinary instance 

 of nursery building, discovered during the exploration of 

 the Paraguayan Chaco by Dr. Budgett. While sitting 

 near the water's edge he saw a female carrying a male upon 

 her back. At last she climbed up the stem of a plant, 

 reached out and caught hold of the tip of an overhanging 

 leaf, and climbed on to it. Both then caught hold of its 

 edges and held them together ; and into the funnel thus 

 formed the female poured her eggs, the male fertilising 

 them as they passed. The jelly surrounding the eggs 

 served as a cement to hold the edges of the leaf together. 

 Then, moving up a Uttle further, the process was repeated 

 until the leaf was fuU, and about a hundred eggs had been 

 enclosed. 



The eggs are peculiar in that they contain much food- 

 yolk surrounded by a quantity of jelly which soon becomes 

 fluid, so that the embryo is seen floating within a glassy 

 capsule. Herein the larval life is also passed, and from 

 the absence of pigment from the skin the external gills 

 assume a crimson colour, imparting to the egg at this stage 

 a singularly beautiful appearance. In due course the 

 tadpole stage is reached. And a most wonderful tadpole it 

 is. At first, transparent as glass, the only conspicuous 

 feature is the eye, which is of a bright metallic green, so 

 that when swimming these jewel-like discs and a bright 

 metallic green spot between the nostrils are all that can 

 be seen. Soon, however, the hind-legs appear. This is 

 the signal for a further astonishing change. The glassy 

 13 



