Germ Cells of Leptinotarsa Signaticollis. 197 



the nucleus and cytoplasm are converted into the inert acid-stain- 

 ing yolk. After fertilization, the basic staining yolk nuclei react 

 with the yolk and convert it from its inert condition into a form 

 which can be readily assimilated by the living protoplasm of the 

 blastoderm. 



Likewise, the nucleus passes through an interesting series of 

 changes. Beginning with the end of the division period, the ground 

 work of the nucleus is a clear, homogeneous, non-staining sub- 

 stance, in which a basic-staining nucleolus and chromosomes are 

 embedded. As the growth proceeds, the chromosomes lose their 

 sharp outline and gradually take on a filmy form in which they 

 stain deeply with acid dye. Finally in the nearly mature egg, 

 all of the nuclear contents appear granular and takes the acid 

 stain, only the nucleoli which have increased greatly in number 

 take the basic stain. 



The Testis 



In the larva each lobe of the testis is of a cylindrical form 

 resembling a single ovariole of the ovary. As in the latter both 

 epithelial and germ cells can be readily identified. In the en- 

 suing stages the increase in size takes place principally at right 

 angles to the axis, but not equally in all directions, being inhibi- 

 ted at regular intervals which mark the spaces between the 

 radiating follicles. The original apex is represented in the adult 

 organ by a cap-like lobe which lies just opposite the aperture of 

 the sperm duct. 



The epithelial investment, at first loosely applied, in late pupa 

 stages enlarges between the follicles and produces the appearance 

 characteristic of the adult in which the follicles are separated 

 from each other by a thick layer of epithelial cells. 



Amitotic division figures of the same type observed in the germ 

 cells of the ovary can be seen in the germ cells of the testis of the 

 larva, the pupa and even the adult in the cap-shaped region. 

 All of the germ cells pass through the amitotic cycle which com- 

 mences at the beginning of cyst formation and persists for a num- 

 ber of cell generations. These cells later divide mitotically. 



Areas of degeneration are to be seen in all stages of the testis 



