OVARY AND OVARIAN EGG OF ANOPHELES 448 
10. The micropyle apparatus is produced by specialized cells 
of the epithelium, the ‘ rosetite-cells ’. 
11. Immediately below the micropyle is a specialized portion 
of the inner wall, the ‘ stopper ’. 
12. The inner and outer walls of the egg, though formed of 
entirely different substances, are both secreted by the follicular 
epithelium. 
13. The inner wall is first gelatinous in nature and trans- 
parent ; but, after the egg is laid, becomes brittle and dark 
in colour, causing the egg to appear black. This change in 
character only takes place when the eggs are laid on water. 
14. The mature egg contains two distinet kinds of yolk, one 
of large granules which are proteid in nature, aud the other 
of small granules the nature of which I have been unable to 
determine. 
15. There are two distinct periods of growth of the ege- 
follicles, the first culminating in the ‘resting stage’ and the 
second only commencing after the mosquito has had a meal of 
blood. 
16. Hach egg-follicle consists of a follicular epithelium 
surrounding seven nurse-cells and an oocyte. These appear 
to be the product of a single oogonium. 
17. The cells of the follicular epithelium multiply by mitotic 
division during the whole of the first period of growth. In the 
second period, though the follicular epithelium increases 
greatly in area, this is due purely to the increase in size of the 
individual cells. 
18. From the earliest stages separate vegetative and germinal 
portions can be distinguished in the oocyte nucleus. 
19. During the second period of growth the oocyte nucleus 
branches throughout the entire oocyte. 
20. The branching nucleus, in conjunction with the nurse- 
cells, takes an active part in the nutrition of the oocyte. 
21. The branching of the nucleus may be regarded as 
a mechanism for the purpose of increasing the surface. 
22. I have observed a similar method of branching of 
the oocyte nucleus in Theobaldia annulata, and it 
