1 76 MUNSON. [Vol. XV. 



that the " inner egg membrane " mentioned by Packard ('71) is 

 the protoderm, the " rudely hexagonal cells " of Packard being 

 the casts of the ends of the blastoderm cells. 



Zones and Yolk-Nucleus. 



The cytoplasm is often divided into two distinct zones — an 

 outer and an inner zone (PI. XIV, Figs. 19, 21, 24, 29). These 

 two zones are often separated by a distinct line suggesting the 

 presence of a membrane between them (PI. XIII, Fig. 16). In 

 other cases the zones are separated by a line of large micro- 

 somes (PI. XIV, Fig. 21). This line may run at a uniform 

 distance from the germinal vesicle (PI. XIV, Fig. 24; PI. XIII, 

 Fig. 16), or it may be extended at the proximal pole towards 

 the stalk (PI. XIII, Fig. 16). Instead of this line of large 

 microsomes, the zones may be separated by parallel fibers 

 resembling those of the polar mitosome. In this line the 

 vitelline-body or sphere may sometimes be observed (PL XIV, 

 Fig. 21). 



The inner zone at times appears less granular than the outer 

 zone, i.e., the granules appear smaller, making the inner zone 

 less stainable than the outer zone (PI. XIV, Fig. 24). In other 

 cases this inner zone consists of large, irregular, closely packed 

 granules that stain intensely in haematoxylin and other chro- 

 matin stains, the outer zone staining less deeply (PI. XIV, Figs. 

 19, 29). This form is of frequent occurrence, and is found in 

 the best preserved material, on the same slide with other eggs 

 showing no trace of it. 



In the living egg of a half-grown specimen these two zones 

 can be distinctly recognized (PI. XIII, Fig. 16). In this case 

 the outer zone is translucent, with the exception of a few scat- 

 tered granules. The inner zone, very sharply separated from 

 the outer zone, is opaque. The germinal vesicle in this case 

 contains a distinct nucleolus. The inner dark zone may form 

 a regular circle around the germinal vesicle (PI. XIII, Fig. 16, b), 

 or it may be extended on the proximal side towards the stalk 

 of the egg, where it seems to become continuous with the 

 protoplasm of the epithelium of the stalk (PI. XIII, Fig. 16, c). 



