Germ Cells of Leptinotarsa Signaticollis. 171 



When adult stages such as represented m Fig. Z, D, are examined, 

 the degenerated area {d. a.) is seen to lie directly beneath the but- 

 ton-shaped region (spg.) and to be encapsulated in a definite cov- 

 ering of epithelial cells, which sharply mark it off from the sur- 

 rounding tissues. 



The process begins in the larva and extends throughout the 

 pupa and adult stages. The first step is an accumulation of epi- 

 thelial cells in the center of the testis, reaching from the opening 

 of the sperm duct back to the cap-shaped area (Fig. Z, C). The 

 region becomes filled with irregular cell fragments that stain deeply 

 with basic aniline dye or with iron-alum-haematoxylin. The cells 

 remaining intact take on a shrivelled and wrinkled appearance 

 and exhibit indications of amitosis, although the latter could not 

 be made out very distinctly, owing to the shrunken condition 

 of the tissue. As the walls of the sperm duct (sp. d.) grow into the 

 testis, the degenerated area retreats, and finally becomes encysted 

 by the surrounding epithelial cells. 



Fig. Z, D, is from a young adult and shows the relation of the de- 

 generated area to the surrounding regions. Above it at spg. is the 

 cap-shaped part filled with spermatogonia, and below it is the gen- 

 eral cavity of the testis packed full of spermatozoa (spz). 



I have noted this curious condition not only in L. signaticollis 

 which had been reared in breeding cages, but also in wild L. decem- 

 lineata, collected from potato vines growing in the open. Therefore 

 the process can not be regarded as a pathological one produced 

 by unnatural conditions accompanying confinement in a cage, 

 but is an event that has a normal physiological significance, which 

 will be considered presently. 



Amitosis in the primary spermatogonia of certain amphibia has 

 been described by La Vellette St. George ('85), Meves ('91), 

 Benda ('93), and McGregor ('99), and the descendants of these 

 cells are said to become functional spermatozoa. King ('07) 

 states that in Bufo lentiginosus amitosis never occurs. An irreg- 

 ular outline is characteristic of the nuclei of the primary sper- 

 matogonia, but the constrictions never lead to actual division. 

 Nussbaum ('01) describes ' ' maulbeerf ormige Kerne," a condition 

 which he maintains is merely a step in the process of mitotic cell 



