390 HARRY H. CHARLTON 



little further beyond the metaphase plate, so that in plate view 

 one pair of chromosomes can be seen to be at a different level 

 (figs. 39 and 40). The side view shows how one limb of the V 

 extends farther than the other. 



The metaphase plate (fig. 38), in which the idiochromosomes 

 are located in the center and surrounded by a ring of chromo- 

 somes, reminds one of the arrangement in some Hemiptera. 



There is little change in the position of these joined chromo- 

 somes in the anaphase (fig. 41), except for a shortening of the 

 connecting thread and possibly a slight movement of the whole 

 toward the distal pole. Figures 42, 43, and 46 picture the 

 telophase arrangement, the idiochromosomes going undivided 

 to one pole. 



There are sixteen chromosomes plus the two idiochromosomes, 

 or eighteen in all, in the first spermatocyte division. Side views 

 have not been counted, owing to the great overlapping of the 

 chromosomes. The plasmosome may be identified during the 

 late prophase (fig. 37), but not definitely after the actual spindle 

 formation. Bodies which are plainly not chromosomes are 

 often seen in relation to the spindle, as the two equal bodies in 

 figure 40, but whether these represent the divided plasmosome 

 or are mitochondrial is not conclusive. 



Resting stage of second spermatocyte 



In the telophase of the first or early prophase of the second 

 spermatocyte (fig. 46), the chromosomes are breaking up. Some 

 appear unchanged, while others have swollen to a spherical shape 

 and stain more diffusely. It is not possible to identify the 

 idiochromosomes at this time, but a little later, when the resting 

 nuclear stage is reached, the double nature of the idiochromo- 

 somes is quite apparent as the nucleolus in one of the now divided 

 cells (figs. 47, 48, 50, and 51). It is not possible to confuse these 

 resting second spermatocytes with the early spermatids, because 

 both nuclear and cell size is much larger. The relative sizes of 

 first and second spermatocytes and spermatids are shown in 

 figure 33, which was diagrammed from measurements of the length 



