WILCOX: SPERMATOGENESIS. 13 
The number relationships of the chromosomes in the spermatogenesis 
of Caloptenus may be thus tabulated : — 
Spermatogonià . . . . . . . . 12 univalent chromosomes. 
Spermatocytes, lst order . . . . . 6 quadrivalent chromosomes. 
Spermatocytes, 2d order . . . . . 6 bivalent chromosomes. 
Spermatids . . . . . . . . . 6 univalent chromosomes. 
Expressed in individual chromosomes : — 
Spermatogonia. . . . . 18 Spermatocytes, 2d order . 12 
Spermatocytes, Ist order . 24 Spermatids®.: sn... 4.94.06 
Spermatids immediately after the second spermatocyte division are 
shown in Plate III. Figs. 125, 129, and Plate V, Fig. 232. There is at 
first no nuclear vacuole surrounding the six small spherical chromo- 
somes, which are closely packed together, and immediately surrounded 
by the granular cytoplasm (Plate III. Figs, 125, 126, 129). The in- 
terzonal filaments are still to be seen, forming a striated body, probably 
the beginning of the “ Nebenkern,” as suggested by Platner (’86). 
Some of the spermatids stained by Henneguy’s method, and nearly 
all of those stained,by Heidenhain's method, show a spherical body near 
the chromatic mass (Plate V. Figs. 232-235), and this body becomes 
included in the nuclear vesicle when a membrane is formed (Plate IV. 
Figs. 140, 141, Plate V. Figs. 232, 236). I regard this body as the 
centrosome which is left in each spermatid after the last spermatocyte 
division, and I also believe it to be identical with the very conspicuous 
body which forms the neck of the spermatozoón (Plate V. Figs, 196-200). 
The chromatie substance fuses into a smoothly contoured mass, which 
soon assumes the crescent shape so common in insect spermatogen- 
esis. The neck-body lies within the nuclear membrane opposite the 
concavity of the chromatic crescent (Figs. 198-200). The chromatin 
undergoes chemical and physical changes during the metamorphosis of 
the spermatid, but the neck-body remains practically the same in size, 
and does not alter its affinity for stains. It becomes the neck of the 
spermatozoón (Plate IV, Figs. 139-158, Plate V Figs. 196-200). The 
chromatic crescent is at first less dense, and stains less deeply ; then it 
becomes concentrated, and stains nearly black by Heidenhain's method. 
These changes in density are not well shown in the figures. At the 
same time it becomes elongated, one end applying itself to the neck- 
body, the other becoming the tip of the spermatozoón head, 
The nuclear vacuolation, much reduced, persists for some time near 
the neck-body (Fig. 196), then disappears entirely, and the further 
