64 ANIMAL PHYSIOLOGY. 
the case of resting ova, changes of a more active character than 
usual are going on in their molecular constitution ; but, on the 
other hand, there may be really a diminution of these activities 
in correspondence with the law of rhythm. This seems the 
more probable. The meaning, however, of a “resting stage” is 
Fie. 67.—Primitive eggs of various animals, cutee amoeboid movements (very much 
enlarged). All primitive eggs are naked cells, capable of change of form. Within the 
dark, finely granulated protoplasm (ege-yelk) lies a large vesicular kernel (the germ- 
vesicle , and In the latter is a nucleolus (germ-spot); in the nucleolus a germ-point (nucleo- 
linus) is often visible. Fig. 4 1—A 4. The primitive egg of a chalk sponge (Leuculmis 
echinus), in four consecutive conditions of motion. Fig. B 1—B 8. The primitive egg of a 
hermit-crab (Chondracanthus cornutus), in eight consecutive conditions of motion (after 
E. Van Beneden). Fig. C 1—C 5. Primitive egg of a cat, in four different conditions of 
motion (after Pilger). Fig. D. Primitive egg of a trout. Fig. E. Primitive egg of a hen. 
Fig. F. Primitive human egg. (Haeckel.) 
the obvious one of apparent quiescence—cessation of all kinds 
of movement. Then ensues rapidly and in succession the fol- 
lowing series of transformations: The nucleolus divides, later 
