84 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
gradually separate (pi. 16, fig. 114). The chromatin segments are 
soon drawn in between the two separating asters, and a new spindle 
is formed (pi. 16, fig. 115). The separation of the new asters is not 
always equally rapid in the two daughter cells of the spermatocyte 
(pi. 16, fig. 115). One spermatocyte second order may even be 
completely divided, while the other has not yet begun to divide (pi. 
16, fig. 116). This may take place while the intermediate fibers of 
the first division still persist. x4s a result of this there may be one 
large cell (spermatocyte second order) connected by half of a divided 
spindle with each of two smaller spermatids, the latter in turn being 
also connected by a spindle (pi. 16, fig. 116). This is not at all com¬ 
mon. Generally the first division is completed before the second 
begins. 
The achromatic figure in the second maturation division is very 
much like that of. the first division; but the chromosomes have a 
decidedly different relation to the spindle fibers. In the first place, 
no equatorial plate is formed. In the second place, it is only the 
central fibers of the spindle that are attached to chromosomes, the 
chromosomes being strung along these central fibers from pole to 
pole. The outer fibers of the spindle are entirely devoid of chromo¬ 
somes (pi. 16, fig. 117). I take this to be due to’the fact that division 
begins before the nucleus is reconstructed after the first division, and 
the fact that, unlike the first division, the separation of the chromo¬ 
somes is not preceded by spireme and tetrad formation. Hence 
there is in this case no division nor splitting of the chromosomes. 
There is merely a sorting of them in such a way that one half the 
original number is drawn toward one pole, the other half number 
toward the other. This of course results in the reduction of the 
number of chromosomes to fourteen in each cell, one half the somatic 
number. 
Orientation of cell and spindle .— The cytocyst being a hollow 
sphere, with the spermatocytes arranged in a single layer next to the 
cyst wall, the cells acquire an outer broad base, and a narrotv inner 
rounded end turned toward the cyst cavity. The nucleus of the 
cell has an eccentric position, being always located near the inner, 
narrow end of the cell. When the spindle develops in the first matur¬ 
ation division, it is always placed in the short axis at right angles to 
the long or vertical axis of the cell and parallel to the cell’s base. 
This results in the division of the spermatocytes into exact halves. 
