THE MONERULA. 



51 



egg-cell of animals, either before or after fertilization, the 

 original kernel disappeared. We explained this phenomenon 

 as a reversion or atavism, and assumed that the egg-cell, 

 in accordance "with the law of latent heredity, first fails 

 back into the kernel-less, cytod stage (Fig. 165). It is only 

 after fertilization is accomplished that a new cell-kernel 

 arises in this cytod, which thus becomes the parent-cell 

 (Cytula, Fig. 166). The transitory kemel-less cytod-con- 

 dition, intermediate between the egg-celi and the parent- 

 cell, is an interesting germ-form, because, in accordance 

 with the fundamental law of Biogeny, it reproduces the 

 origina], oldest parent-form of the Moneron; we therefore 

 call it the Monerula, (Cf vol. i. pp. 178-183.) 



f Fig. 165.— Monerula of Mammal (Rabbit). The fertilized egg-cell after 

 the loss or the nucleus is a simple ball of protoplasri (d). The outer covering 

 of the latter is formed bj the modified zona pellucida (z) together with 

 a rnucous layer (h) secreted on to the outside of the latter. In this a few 

 sperm. cells are still visible ^s). 



Fig. 166.-Parent-cell (CyUda) of a Ma'_>imal (Eabbit) : k, parent, 

 kernel ; n, nucleolus of the latter ; p, protoplasm of the parent-cell ; z, 

 modified zona pellucida ; s, sperm-cells ; h, outer albuminous covering. 



