MUNSON: SPERMATOGENESIS OF PAPILIO. 
67 
tively large and distinct spindle, having the twenty-eight spherical 
chromosomes arranged perfectly in the equatorial plate. This phase 
is very common (pi. 15, fig. 57a, d). The chromosomes then split,, 
each half being drawn to an opposite pole of the spindle. The sepa¬ 
ration and the movement toward the poles is accomplished with the 
utmost regularity, making beautiful dyasters. The anaphase is 
evidently passed through much more rapidly than the metaphase 
or telophase, as it is rarely seen (pi. 15, fig. 57a, e). The telophase 
(pi. 15, fig. 57a, /) is frequently to be seen, the beautiful intermediate 
fibers of the spindle remaining apparently for a long time after the 
separation of the chromosomes is completed. In only one instance 
have I seen as many as four mother branch cells belonging to the same 
grandmother cell dividing at the same time (pi. 15, fig. 57a). Usually 
only one is seen in mitosis. 
Without exception, the spindle is arranged in the long axis of the 
cell, and consequently vertically to the surface of the grandmother 
stem cell. This arrangement of the spindle results, as the cytoplasm 
constricts at the equator, in the division into two unlike and unequal 
parts — a distal spherical cell (p. g.), and a proximal conical cell (7), 
connected as w T as the original mother cell with the central grandmother 
cell. 
The peripheral, spherical daughter cell (p. g.) becomes detached 
from its sister, and is, in fact, a primary spermatogone. The proxi¬ 
mal daughter cell retains the original character of the mother stem 
cell, occupying the same position and still connected with the grand¬ 
mother cell. After growing to its original size it evidently divides 
in the same manner again and again thus giving rise to a succession of 
primary spermatogones somewhat as a branch of some trees gives rise 
to new buds to replace those that drop off, a single tree thus becoming 
the parent of a forest. 
As the primary spermatogone is thus pinched off in karyokinesis 
from its sister cell — the mother branch cell — one or more of the cor¬ 
tical nuclei also accompany it, and are later developed into the 
cyst cells (pi. 15, fig.. 57a, k). A section through the cells (br. c .) in 
the plane indicated by the dotted line is represented in plate 15, figure 
57b, where the relation of the mantle nuclei to the mother branch 
cells is clearly seen. They form a circle of three or four nuclei 
around each cell. The same relation is, of course, obtained in a 
similar section through primary spermatogones. 
