DAVIS: SPERMATOGENESIS. 103 



E. Melanoplus femoratus. 



During the maturation period bivalent autosomes of the same tyjies 

 as in Dissosteira can be recognized and evidently divide in the same 

 way. 



In the case of the monosome, which at the end of the growth period 

 is divided into two distinct components — one more or less rounded 

 with smooth contours, the other elongated and granular — both com- 

 ponents become homogeneous and V-shaped during the early matura- 

 tion period (Plate 7, Figs. 120-122). Finally in the late prophase of 

 the first maturation division the components probably become joined 

 end to end to form a longitudinally split rod. As in the preceding spe- 

 cies, the monosome fails to divide during the first division. Figure 74 

 (Plate 5) shows the metaphase of the first division. The monosome, 

 although lying in the equatorial plane, is evidently attached at its end 

 to mantle fibers from only one pole, while the opposite end curves 

 away from the spindle. During the second division the monosome 

 divides longitudinally. 



F. Stenobothrus curtipennis. 



1. Autosomes. 



In Stenobothrus the tetrads are formed much as in Dissosteira, but 

 the structure and division of the autosomes are especially well shown. 

 At the beginning of the maturation period (stage g, Plate 6, Fig. 83) 

 the loops of the polar spireme have become freed from the nuclear 

 membrane and the longitudinal splitting is very distinct, though never 

 as wide as in Dissosteira. In stage h (Figs. 84, 85) each loop has 

 become converted into a definitive tetrad. There are three especially 

 large tetrads whose structure is very well shown, and these are the only 

 autosomes I shall follow through the maturation period. The smaller 

 autosomes are essentially like those described in Dissosteira and 

 exhibit no new features. The three larger autosomes are, however, 

 of especial interest, since they show the sequence of the maturation 

 divisions in a very conclusive way. These three elements are evi- 

 dently formed by the conjugation of the three pairs of larger univalent 

 autosomes of the spermatogonia. At first they are much longer than 

 the diameter of the nucleus, and each is plainly composed of two 

 longitudinally split arms, which lie close together and are often more 

 or less twisted around each other. 



