38 



GERM-CELL CYCLE IN ANIMALS 



ooc 



Fig. 7. — Leptinotarsa de- 

 cemlineata. Diagram of 

 an ovarian tubule showing 

 various stages in the de- 

 velopment of the oocyte. 

 The capital letters refer to 

 the positions f cells shown 

 in Fig. 8. cy = cytoplasm; 

 es = egg string; n.c = nurse 

 chamber; doc = oocyte; y.o 

 = young oocyte. 



and cytoplasmic structures 

 are shown in Fig. 8. Two 

 oocytes and a neighboring 

 epithehal cell from position 

 A in Fig. 7 are shown in Fig. 



The nuclei of the oocytes 

 are large and contain a dis- 

 tinct spireme ; the cytoplasm 

 is small in amount and ap- 

 parently homogeneous. After 

 a short period of growth the 

 oocytes form a linear series 

 in the ovarian tubule and 

 become connected with the 

 spaces between the nurse cells 

 by means of egg strings (Fig. 

 7, e.s) through which the nu- 

 tritive streams flow into the 

 oocytes. One of the young- 

 est of these oocytes is repre- 

 sented in Fig. 8, B (position 

 B in Fig. 7). The nucleus is 

 no larger than in those of the 

 earlier stage ; its chromatin 

 forms a reticulum, and a dis- 

 tinct nucleolus is present. 

 The cytoplasm, on the other 

 hand, has trebled in amount 

 and within it are embedded 

 a number of spherical bodies 



