500 Alice M. Boring 



phase, while the tetrads are forming (Fig. 269), the plasmosome 

 sometimes not being dissolved until after the spindle is formed 

 (Fig. 271). There are 14 chromosomes in the equatorial plate of 

 the first spermatocyte (Fig. 270), one of them being marked by its 

 eccentric position, another by its large size. This large chromo- 

 some keeps its individuality in all the second spermatocytes, those 

 with 14 chromosomes (Fig. 273), and those with 13 (Fig. 274). 

 The odd chromosome does not divide in the first spermatocyte 

 division (Figs. 271 and 272), but does in the second (Figs. 275 and 

 276). The development of the spermatid in this family is very 

 peculiar. The nucleus stains quite deeply, so that nothing more 

 can be made out than that there seems to be one condensed body in 

 each spermatid (Fig. 279a). The "Nebenkern" goes through a 

 complicated development somewhat similar at first to that de- 

 scribed by Baumgartner ('02). First delicate fibers are formed in 

 it (Fig. 277), then it appears as a long coiled fiber in a clear space, 

 surrounded by a definite membrane (Fig. 278). This space 

 becomes separated by a partition into two tubes, each containing 

 several shorter fibers (Figs. 279a and b). These tubes and fibers 

 both become elongated (Fig. 280). The tubes grow still longer 

 and smaller in diameter, and at the same time twist around each 

 other in an irregular spiral (Fig. 281a). Cross sections through 

 different portions of these twisted tubes indicate that they must 

 also be constricted in places (Fig. 281b). They finally become 

 flattened, presenting some such an appearance as in Fig. 282a, 

 and in cross section as in Fig. 282b. In this species, the chromo- 

 somes in the female somatic cells could be counted, and proved to 

 be 28 in number (Fig. 283), there being the same two long ones that 

 appeared in the spermatogonial plate. The significance of the 

 even number in the female, and the odd number in the male will 

 be pointed out in the theoretical considerations. 



Poeciloptera pruinosa 



Poeciloptera pruinosa resembles the last described form exter- 

 nally in every character but color, being a grayish purple instead 

 of a pale green. The principal stages are shown in Figs. 284 to 293, 

 the only diff'erence being that there are two large chromosomes 



