222 Farmer and Reeves. — On the Occurrence of 
in a case like the present, to escape the conviction that there 
exists a close relation between the spindle and the nuclear 
wall, over which the radiations have been extending. The 
centrospheres frequently become difficult to distinguish at 
this stage, and the polar radiations are often hardly visible. 
The achromatic spindle apparently ends sharply at a point, 
but we have convinced ourselves, as the result of a careful 
examination of a somewhat extensive series of preparations, 
that the spindle does not, as a matter of fact, terminate in the 
general cytoplasm, but that its two apices are respectively 
occupied by two (sometimes only one) corpuscles, and we 
believe we are justified in regarding these as the representatives 
of the centrospheres, although they do not exhibit a degree of 
clearness such as that described by Schottlander 1 for the 
antherozoid-mother-cells of Marchantia. On the other hand, 
the radiations are obvious here, while Schottlander states that 
with one exception these did not occur in the plants investi- 
gated by him. 
After the separation of the chromosomes from the equator 
to form the daughter nuclei, a beautiful cell-plate is formed 
across the achromatic spindle, by local thickening of the 
4 Verbindungsfaden,’ and it then extends centrifugally, finally 
meeting the peripheral wall of the cell, exactly as in the higher 
plants. 
During the reformation of the daughter-nuclei the radiations 
above spoken of at first become again more distinct, but they 
finally die away altogether, and in the completely resting 
nuclei they are entirely wanting. When this stage is reached 
we do not succeed in definitely detecting the presence of 
a centrosphere or centrosome, and we do not regard it as 
probable that these structures retain their individuality within 
the cytoplasm in the case of Pellia. It is easy enough to 
find bodies of minute size, surrounded by their diffraction 
areas, but it would be pure empiricism to fix on any one or 
1 Schottlander, Beitr. z. Kentniss d. Zellkerne u. d. Sex. Zell. b. d. Kryptogamen. 
Cohn, Beitr. z. Biol. d. Pflanzen, Bd. VI, 1892. 
