418 ROBERT W. HEGNER 



described and figured the pole-disc in the egg of Leptinotarsa 

 decemlineata which was preserved shortly before deposition. 

 Since that time a complete series of oocytes have been prepared 

 and examined for the purpose of tracing the history of these 

 granules. 



The positions of the stages to be described are indicated in 

 the diagram (fig. 9) and the nuclear and cytoplasmic structures 

 are shown in figures 58 to 67. Two oocytes and a neighboring 

 epithelial cell from position 58 in figure 9 are shown in figure 58. 

 The nuclei of the oocytes are large and contain a distinct spireme; 

 the cytoplasm is small in amount and apparently 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 eggs strings (fig. 9, e.s.) 

 through which the nutritive streams flow into the oocytes. 

 One of the youngest of these oocytes is represented in figure 59 

 (position 59 in fig. 9). The nucleus is not larger than in those 

 of the earlier stage; its chromatin forms a reticulum, and a 

 distinct nucleolus is present. The cytoplasm, on the other hand, 

 has trebled in amount and within it are imbedded a number of 

 spherical bodies which stain with crystal violet after Benda's 

 method, and appear to be mitochondrial in nature. At a slightly 

 later stage (fig. 60, position 60 in fig. 9) the nucleus is larger and 

 contains several small spherical chromatic bodies besides the 

 nucleolus. The cytoplasm has increased more rapidly in volume 

 and a corresponding increase in the number of mitochondrial 

 granules has also taken place. Further growth results in an 

 increase in the volume of both nucleus and cytoplasm (fig. 61, 

 position 61 in fig. 9), and a slight increase in the number of 

 mitochondria. Whether these bodies developed de novo or by 

 division of the preexisting granules could not be determined. 



In succeeding stages growth is very rapid. The cytoplasm 

 (fig. 62, position 62 in fig. 9) still remains homogeneous except 

 for the mitochondria which increase slightly in size and become 

 situated as a rule near the periphery. The nucleus at this time 

 contains a large number of chromatin granules and a diffuse 

 reticulum. Part of an older oocyte is shown in figure 63 (posi- 



