ON THE SPERMATOGENESIS OF THE SILK-WORM. 
137 
mass collecting in the centre of a nucleus, but no resting stage 
is formed. The fate of the centrosomes is not known. The 
collected chromosomes gradually separate from one another and 
form a loose mass of chromatin granules. 
A full grown spindle with a “ Kernplatte ” is again formed. 
Owing to the reduced size of the cell-body after the first division 
(compare figs. 51 and 52 with figs. 54 and 55 all of which are 
magnified to the same diameter), the spindle together with that 
of the individual chromosome is very small in this spindle, so 
that we can easily distinguish it from the spindle of the first 
division. A side view of a cell in this second division is shown 
in fig. 54. In this division, the chromosomes are arranged in a 
single row, and no constriction is to be seen in any of them. In 
the polar view of the “ Kernplatte,” twenty-eight chromosomes 
can be counted (fig. 55). These separate into two groups and 
form the chromosomes of sperm-daughter-cells, each of which 
therefore contains fourteenxhromosomes. Fig. 56 represents the 
diaster of this stage. The exact number of the chromosomes 
can not be made out in the side view, but in the polar view we can 
clearly count fourteen (fig. 58). Sometimes, a darker structure, 
somewhat resembling the “ Verbindungsbrücken,” is to be seen 
under the polar spindle (fig. 57, lower figure), but I am not able 
to tell what this really represents. 
A single or a double row of cell-plates appear at the equator 
of the “ Verbindungsfäden ” (Figs. 58, 59, 60) and the cell be¬ 
comes constricted. The central and the polar spindles can now 
be clearly distinguished from one another (Fig 59). The former 
appears as a compact mass presenting a median darkly stainable 
part, while the polar spindle forms a somewhat semicircular 
ring having a centrosome in its centre. 
The daughter-cells, after these changes, completely separate 
from each other. These we call sperm-daughter-cells which 
correspond with the “ Spermatides ” of la Valette St. George. 
IV. The Stage of Metamorphosis. In this stage, the sperm- 
daughter-cells gradually change themselves into spermatozoa. In 
figs. 61 and 62 we have five sperm-daughter-cells.- The “Verbin¬ 
dungsfäden ” gradually contracts, accumulating in its end some 
microsomes (fig. 62 a, b). These “ Verbindungsfäden ” become 
gradually coarser, as is represented by fig. 62 c, m , and finally 
