DAVIS: SPERMATOGENESIS. 100 



c}ies the autosomes become broken down to a greater extent than in the 

 Acrididae, and the chromatin is scattered through the nucleus in 

 irregular masses (Fig. 193). I have, however, been unable to dis- 

 tinguish any nuclear membrane at this stage, although the nucleus is 

 well defined. Figure 194 is a prophase of the second maturation 

 division, the longitudinal split in the large autosome being clearly 

 shown. Figure 195 shows the metaphase, and Figures 196 and 197 

 different stages of the anaphase of the second di\'ision. In the large 

 autosomes this division is plainly longitudinal and equational, since 

 it is, in all probability, along the plane of the longitudinal split. Here, 

 again, the plane of division cannot be determined in the remaining- 

 autosomes, but is probably longitudinal. In Figures 198 and 199 is. 

 shown the beginning of the telophase of the second division. 



Thus, in the case of the large bivalent autosome both di\'isions are 

 longitudinal, although the first is really a reducing di^^sion. In the 

 other autosomes the first division is ])robably transverse, the second 

 longitudinal. I have been unable to find the slightest endence that 

 both maturation divisions are transverse, as is held by Otte (:06) to 

 be the case in Locusta. 



2. Monosome. 



The monosome in Steiroxys, unlike that in most of the Acrididae, 

 can be easily followed throughout both maturation divisions. At the 

 beginning of the maturation period the monosome, which in the pre- 

 ceding stage formed a flattened vacuolated plate, becomes more 

 compact and is soon converted into a U-shaped element (Plate 7, Figs. 

 155-158) by the development of a longitudinal split. It is interesting to 

 note that the monosome has at this time practically the same form as 

 during the early growth period, except that it is now much shortened 

 and thickened. The arms of the U become closely apposed and 

 during the metaphase of the first maturation division (Plate 5, Fig. 73) 

 the monosome is seen as a longitudinally split rod lying nearer one 

 spindle pole than the other. It usually lies in the cytoplasm at a short 

 distance from the spindle, but in favorable cases can be plainly seen 

 to be connected by mantle fibers with the nearest pole. As in the 

 Acrididae, the monosome (Plate 8, Fig. 190) does not divide during 

 the first division. In the majority of cases it passes to one pole of the 

 spindle with the autosomes, but occasionally it lags behind (Fig. 191). 

 In such cases it never enters the nucleus of the secondary spermato- 

 cyte, but lies outside in the cytoplasm, where it forms a conspicuous 

 U-shaped element. Figure 193 represents two adjoining secondary 



