398 BOTANICAL GAZETTE [DECEMBER 
straight may owe their appearance to the manner in which they 
have been sectioned; and such is undoubtedly the case from 
the position of the poles and the difficulty in making an exact 
meridional section. This shape seems to be due to the rapid 
lengthening of the spindle threads as soon as they have come 
together at the center. Spindles are often curved, or rather it 
happens that the poles do not have a common axis. This is 
observed in their formation, however, and before the centrosomes 
have taken diametrically opposed positions. The daughter 
segments separate and pass rapidly toward the poles, along the 
spindle fibers, which have now become straight. Here they 
crowd so closely together that they lose their individuality and 
appear as a broken mass of chromatin, which soon becomes 
enveloped in a new membrane forming the daughter nuclei (fig. 9). 
The centrosomes become invisible or perhaps dissolve as 
soon as the polar radiations have disappeared. The connecting 
fibers now thicken in the equatorial region, the first indication of a 
cell plate (figs. 9, zo). This thickening begins at the center of 
the equatorial plane and gradually extends to its circumference, 
apparently pushing the fibers farther apart toward the cell 
membrane, until the spindle becomes very much bulged or 
rounded. 
Concomitant with the bulging of the spindle, its connecting 
fibers begin to shorten and to dissolve at the poles (fig. 71). 
As they disappear toward the Cell plate, which finally reaches 
the membrane, dividing the old cell completely, the daughter 
nuclei follow, and come to lie very near each other (jig. 7 2). 
Thus the process of cell plate formation is almost identical 
with what I find in Anthoceros. It corresponds also with that 
described by Mottier (’97) for Lilium. 
ANDERSON, INDIANA. 
: LITERATURE CITED. 
CAMPBELL, D. H.: Mosses and Ferns. 1895. 
Davis, B. M.: The spore mother cell of Anthoceros. Bot. Gaz. 28: 89. 1899. 
FARMER, J. B. and REEVES, Jesse: On the occurrence of centrospheres 10 
Pellia epiphylla Nees. Ann. Bot. 8: 219. 1894. 
