206 Harry Lewis Wieman. 



EXPLANATION OF FIGURES 



Fig. 1. Longitudinal section of ovariole of larva. 



Fig. 2. l^ongitudinal section of ovariole of pupa. 



Fig. 3. Longitudinal section of ovariole of pupa one day older than the preceding 



Fig. 4. Transverse section of tei'minal chamber of pupa; same age as preceding. 



Fig. 5. Longitudinal section of terminal thread at its maximum degree of devel- 

 opment ; four days older than the preceding. 



Fig. 6. Longitudinal section through the proximal end of the terminal chamber, 

 showing a sharp line of demarcation between the latter and the ovariole-stalk; 

 same age as the preceding. 



Figs. 7, 8 and 9. Sections through the same region showing succeeding stages, 

 which illustrate the efTacement of the line of demarcation between the cells of the 

 terminal chamber and those of the ovariole-stalk through the production of a 

 semi-fluid mass in which epithelial nuclei are embedded. 



Fig. U. Longitudinal section through the same region as the preceding, show- 

 ing the formation of egg-strings in the adult. 



Fig. 12. Longitudinal section showing egg-string at its maximum degree of 

 development. 



Fig. 13. Longitudinal section of the distal end of the ovariole whose proximal 

 end is shown in Fig. 11. 



Fig. 14. Longitudinal section of terminal chamber in region of nurse-cells of a 

 somewhat maturer adult. 



Fig. 15. Longitudinal section of ovariole showing the formation of cysts among 

 the nurse cells lying adjacent to the young oocytes; very young adult. 



Fig. 16. Transverse section through the middle of the terminal chamber show- 

 ing well developed cysts; mature adult. 



Fig. 17. Longitudinal section of larval testis; cysts just beginning to form. 



Fig. 18. Later stage of preceding; two days older. 



Fig. 19. Tripolar spindle; common among nurse cells before amitosis sets in. 



Figs. 20-23 inclusive. Four stages in amitotic cell division as seen in the nurse- 

 cells. 



Figs. 24-32 inclusive. Illustrate peculiar transformations undergone by certain 

 of the nurse cells. For full description see the text. 



Fig. 33. Represents a section of the ovum from the region where the yolk and 

 nutritive stream adjoin. The nutritive stream consists of red basis-staining 

 granules (to the right) which spread along a reticular network in the meshes of 

 which the green acid-staining yolk is deposited (to the left). 



Figs. 34, 35. Two stages in amitosis in the primordial germ cells of the larval 



ovary. 



Fig. 36. Germ cell from the pupal testis showing its relation to the surrounding 

 epithelial cells. 

 Fig. 37. Germ cell from the pupal ovary showing the same relationship. 



