106 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
autosomes divide along the plane of the longitudinal split which first 
appeared in the polar spireme of the primary spermatocyte. The 
second maturation division is therefore an equational division. Figure 
V. We: oe 
Fic. T.— Polar view, metaphase of second maturation division of Stenobothrus 
curtipennis. Nine chromosomes. The monosome is present. XX 1450. 
Fig. U.— Polar view, metaphase of second maturation division of Stenebothrus. 
curtipennis. Eight chromosomes. The monosome is absent. x 1450. 
Fic. V.— Polar view of daughter chromosomes, anaphase of first maturation 
division in Steiroxys trilineata. X 1450. 
Fic. W.— Polar view, metaphase of second maturation division in Steiroxys 
trilineata. Fifteen chromosomes. The monosome is present. XX 1450. 
Fic. X.— Polar view, metaphase of second maturation division in Steiroxys trili- 
neata. Fourteen chromosomes. The monosome is absent. X 1450. 
97 shows the anaphase and Figure 98 the telophase of the second 
maturation division. 
2. Monosome. 
It still remains to follow the monosome of Stenobothrus through 
the maturation period. At the end of the growth period this element 
is plainly composed of two distinct parts (Plate 3, Fig. 52), one of 
which is rounded, has smooth contours, and is vacuolated, while the 
other is elongated, has a ragged outline, and is granular. In the fol- 
lowing stage (g) the granular part shortens and becomes more com- 
pact, meanwhile being bent into a V-shape (Plate 7, Figs. 140-141). 
