82 BOTANICAL GAZETTE [aucust 
recently succinctly reviewed by Ballowitz,? so that I need not 
go over it here. Ballowitz finds that the midbody is formed by 
the fusion of swellings of the central spindle fibers. _ His obser- 
vation differs from Flemming’s in that the latter thought the 
granules were sometimes between the fibers. Ballowitz and 
Flemming agree that the midbody takes no part in the division 
of the cell, but may be seen between the two daughter cells 
after division is complete. Ina very interesting paper by Kos- 
tanecki,° upon the relation of polar radiations to the division 
of the cell body, the view is developed that the division is 
effected by a cell plate built in the cytoplasm by means of two 
systems of polar radiations which connect the granular cell 
boundary with the centrosomes. During the metaphases the 
longer fibers from éach centrosome, which cross each other ia _ 
the equatorial region of the cell, contract and so change their 
points of attachments to the plasma membrane until they reach | 
the equator. They now draw in toward the central spindle, pull 
ing in with them a substance similar to that of the cell boundary; 
i 
oe 
Descriptive, 
The present investigation was undertaken to attempt to “ 
mine in detail the exact sequence of events. during the divis! 
of the cell body, and to correlate, so far as possible, the fact 
* Zur Entstehung des Zwischenkorpers. Anat. Anz. 14: 390. | 
ai Ueber die Bedeutung der Polstrahlung wiahrend der Mitose u. ihr. veri 
zur Theilung der Zellleibes, Arch. f. mikr, Anat. 49: 651. : : 
