XII 



PHYLUM CHORDATA 



427 



black and one white hemisphere, the former always directed 

 upwards, and is surrounded by a sphere of jelly. During 

 oviposition the male sheds his spermatic fluid over the eggs, 



FIG. 242. Rana temporaria. Stages in the life-history, from the newly-hatched 

 Tadpoles (/) to the young Frog (<?). 2a is a magnified view of 2. (From 

 Mivart.) 



and the sperms make their way through the jelly and 

 impregnate them. 



When the embryo escapes from the egg by the rupture of 

 the egg-membrane it swims about as a little fish-like creature 



