108 bulletin: museum of comparative zoology. 



Fig. 82) is easily distinguishable in the spermatid for some time, as 

 its disintegration takes place much later than that of the autosomes. 



G. Steiroxys trilineata. 



1. Autosome. 



At the close of the growth period the loops of the polar spireme 

 become freed from the nuclear membrane, as in the Acrididae. More- 

 over, the chromatin and linin become much concentrated so that in 

 stage g (Plate 5, Fig. 70) the diameter of the threads is much less than 

 during the preceding stage. At the same time, as a result of the 

 aggregation of the chromatin, the longitudinal split reappears. Some- 

 what later the loops have become converted into tetrads, which stain 

 deeply and have such a ragged outline that it is almost impossible to 

 determine their structure; but they have apparently (Figs. 71, 72) 

 forms similar to those of the Acrididae. There is always one tetrad 

 which is much larger than the others and is undoubtedly formed from 

 the two large autosomes of the spermatogonia. The form of this 

 tetrad is well shown in Figure 71. It is apparently formed by the 

 arms of the loops becoming twisted around each other, and, as in the 

 Acrididae, each of these arms no doubt represents a univalent auto- 

 some. During the late prophase of the first maturation division this 

 autosome becomes disposed on the spindle with its long axis at right 

 angles to the axis of the spindle (Fig. 73). In addition to the large 

 element there are thirteen smaller autosomes (Plate 8, Fig. 189), which 

 have approximately the same size relations as the autosome pairs of 

 the spermatogonia. In the case of the large autosome the following 

 division is apparently longitudinal, but, judging from analogy with 

 the Acrididae, results in the separation of its univalent components. 

 As the two components separate (Fig. 190) each is split longitudinally 

 and is e\ddently composed of two curved rods lying side by side. In 

 the case of the smaller autosomes I have found it impossible to deter- 

 mine their orientation on the spindle with any accuracy, but, as in the 

 large autosome, the first division is probably reducing. As the small 

 autosomes separate (Fig. 190), their dyad structure is usually apparent, 

 although the longitudinal split is often difficult to distinguish and can 

 best be seen in polar ^^ews of the anaphase (Fig. V, p. 106). Figure 

 191 shows the beginning of the telophase, the autosomes being collected 

 in a mass near the poles of the spindle, m hile Figure 192 is a late telo- 

 phase. During the "semiresting stage" of the secondary spermato- 



