SECRKTION IN FOLLICLE CELLS. 21 1 



ovarian egg is provided, is elaborated through the agency of the 

 follicle cells. These assume intense secretory activity during 

 the later stages of the oocyte's development, a time coincident 

 with their own period of amitotic division. This paper contains 

 an account of the nuclear and cytoplasmic phenomena of the 

 amitotic cells of the cricket egg-follicle, observed in specimens 

 living and fixed, during their period of secretory activity. 



The investigation was carried out for the most part at Wash- 

 ington University, Saint Louis, in 1923 and 1924 under the 

 direction of Professor Caswell Grave. Additions and revisions 

 were made at the Hull Zoological Laboratory of the University 

 of Chicago in the fall of 1924, by the courtesy of Professor 

 F. R. Lillie. It is a pleasure to take this opportunity of ex- 

 pressing my thanks to Dr. Grave for valuable suggestions and 

 criticisms; and to Dr. Margaret Reed Lewis, for suggestions 

 relating to the technique of tissue cultures. 



II. MATERIAL. 



The cricket ovary consists of a bundle of egg-tubes situated 

 in the posterior part of the abdomen, ventro-lateral to the 

 digestive tract, and communicating by means of a short oviduct 

 with the vagina. Each egg-tube contains a number of eggs 

 (usually from 8 to 12 at a time), arranged in linear series according 

 to size; the largest and most mature egg being adjacent to the 

 oviduct, and the smallest located at the opposite end of the 

 egg-tube, connected distally with a "nest" of undifferentiated 

 cells. (See Fig. 15.) The egg-tube, or follicle (which descends 

 with the egg), is one layer of cells in thickness. Between the 

 egg and its follicle a rather thick vitelline membrane intervenes 

 which exhibits hexagonal markings that correspond with the 

 outlines of the bases of the superimposed follicle cells. The 

 follicle cells themselves are of an epithelial nature, and approxi- 

 mate hexagonal prisms in shape, varying in proportions with age 

 (to be discussed more fully further on) from the columnar to 

 the squamous type. Except at the proximal end, where it is 

 attached to the oviduct, the egg tube lies within the heemocoel 

 of the insect; but contact with the blood is prevented by a 

 thin, closely investing membrane. 



The species of cricket used for study were, Gryllus abbreviatus , 

 15 



