146 MUNSON. [Vol. XV. 



cavity in which the egg lay becomes practically obliterated by 

 the stretching of the walls of the ovarian tube to accommodate 

 the eggs within it, and only later bulges out as an empty 

 follicle, after the tension within is relieved on the discharge of 

 the eggs in oviposit ion. 



Concerning the role which the radial protoplasmic fibers of 

 the chorion may have in the transfer of nourishing material 

 from without, I have nothing on which to base any positive 

 statements. Neither do I know whether these fibers are 

 retracted within the egg, thus leaving pores after the discharge 

 of the egg from the follicle. It may be supposed, perhaps, that 

 they serve somewhat as delicate pseudopodia in the transfer of 

 nutriment. Among others, Eimer ('72) has ascribed such a 

 function to them in the egg of reptiles. 



However that may be, the fact remains that the eggs 

 increase greatly in size and become unfavorable for sectioning, 

 a feature that does not exist up to this time. 



Stages of Growth. 



The period of growth extends from the last division of the 

 oogonia to form follicles to a somewhat indefinite period after 

 the e^g has entered the ovarian tube and has attained its full 

 size. By regularly recurring internal phenomena this period 

 divides itself into four stages. First, a stage extending from 

 the beginning of growth to the formation of the first layer of 

 the egg membrane. Second, a stage extending from the end 

 of the first to the time when the germinal vesicle begins to 

 move towards the periphery. Third, a stage beginning with 

 the gradual approach of the germinal vesicle to the periphery 

 of the egg and terminating with the discharge of the egg into 

 the ovarian tube. Fourth, a stage extending from the time of 

 entrance into the ovarian tube to the time of oviposition. 



Each stage may be first briefly described, after which the 

 history of each part of the egg will be considered separately. 



Stage I. — The most striking peculiarity of the growing egg 

 at the time when it can first be recognized as such is the deeply 

 stainable granular cytoplasm which, previous to growth, is char- 



