pinney: chromosomes of anasa tristis. 353 



The testes of Anasa tristis are paired organs in the form of 

 two small fig-shaped bodies which lie on either side of the 

 median line in the cephalo-ventral part of the abdominal cav- 

 ity. They are composed of a number of long, slender follicles 

 lying parallel to each other and extending the entire 

 length of the testis. The follicles themselves taper slightly 

 from the broader base toward the sperm-duct. The follicu- 

 lar organization into cysts of germ cells of varying stages 

 of maturation is similar to that in the Orthoptera, and the 

 same method which was used to determine the sequence of 

 the observed changes in the Orthopteran species is applicable 

 here. Practically all of the cells of a cyst are in the same 

 phase, although exceptions to this regularity are frequent in 

 the older cysts, particularly those of the first and second sper- 

 matocyte generations. These variations are, however, to be 

 expected, and may reasonably be accounted for if one considers 

 the unavoidable differences which must occur in the rate of 

 metabolism in cells situated differently in the same cyst. 



The longitudinal section of a follicle presents some noticeable 

 features of a structural nature caused by characteristic dif- 

 ferences in the cells of various regions. The spermatogonial 

 cells occupy the distal portion of the follicle, the extent of the 

 spermatogonial area being determined by the age of the in- 

 dividual. These cells are small, and in the older cysts the nu- 

 cleus is accompanied by little cytoplasm. Hence the peculiar 

 staining quality of the nuclear material causes this region to 

 appear more intensely stained than the proximal portion of the 

 follicle. The cells, too, are crowded closely together. In con- 

 trast to this is the lightly stained spermatocyte region, due to 

 the fact that here the cells contain a greater amount of cyto- 

 plasm in proportion to the amount of nuclear material. The 

 cells have increased so greatly in size in the later generations 

 that the cysts are larger. Usually a characteristic barrier ex- 

 ists between the two main regions of divisions. This is formed 

 by cysts of cells undergoing the process which has been desig- 

 nated as synizesis, a detailed description of which will come 

 later. In almost every instance, too, the line of separation is 

 emphasized by the presence of many cysts of degenerating cells 

 with their spherical masses of chromatin. 



