DAVIS: SPERMATOGENESIS. 103 
E. Melanoplus femoratus. 
During the maturation period bivalent autosomes of the same types 
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. 
