268 C. T. BRUES, 
Explanation of Plates. 
Plates 22nd 23. 
Plate: 
Fig. 1. Section through several primitive eggs. The two upper 
eggs are cut through the center and the lower one tangentially. f.e 
follicular epithelium investing the primitive eggs. p.c cells destined 
to form the polar cap. 
Fig. 2. Median longitudinal section through an egg just before 
the secretion of the yolk has begun. p.c polar cells. yk first be- 
ginning of the yolk mass. n.c nurse cells. f.e follicular epithelium 
of extremely flattened cells which now encloses the egg. 
Fig. 3. Median longitudinal section of an egg which is being 
supplied with yolk. Lettering as in Fig. 2. 
Fig. 4. Median longitudinal section of a nearly ripe egg. Let- 
tering as in Fig. 2. 
Fig. 5. Median longitudinal section through an abnormal egg. 
Some of the nurse cells have failed to become transformed into yolk 
and can be seen at the bottom of the figure (d.n.c). The follicular 
wall (f.e) is very thick. At the surface of the yolk a perfectly normal 
egg nucleus (vw) can be seen which is ready to undergo the maturation 
phenomena. 
Fig. 6. Median longitudinal section through a fertilized egg 
showing the single large cleavage cell in the center with its radiating 
protoplasmic projections. The external wall of the egg is not shown 
in this figure. 
Fig. 7. Median longitudinal section through an egg in the blasto- 
derm stage (86 cells). Bl blastoderm. Ch chorion. 
Fig. 8. Median longitudinal section through an egg just as the 
blastoderm has drawn up to one pole of the egg. Blh vestiges of the 
Blastodermhaut. G.Bd rudiment of the germ band. In this figure the 
egg envelopes are omitted. 
