PORIFERA, CQ@ELENTERATA, VERTEBRATA 105 
structure concludes that it is not a special cell organ 
but an artifact. Kulesch (1914), on the contrary, 
finds it to be a constant organ in the eggs of the cat, 
dog, and guinea-pig. 
The evidence of a continuous germ-cell cycle in 
the vertebrates is more convincing than in the 
sponges and ccelenterates, and leads us to predict 
that it will not be long before the gap still existing 
during which germ cells cannot be recognized will 
be filled in to the satisfaction of the majority of 
investigators. 
