198 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



surrounded by the granular zone (fig. 12), forms the spin- 

 dle. It projects out at various points to form cones in which 

 the meshes are gradually stretched and finally form free 

 fibers (fig. 13). The whole reticulum inside of the gran- 

 ular zone finally becomes transformed into such cones. 

 These at first point in all directions, but finally form two 

 groups (fig. 15). In each of these groups the poles fuse 

 to form a single one, thus producing the bipolar spindle. 



The spindle is formed by the rearrangement of pre-exist- 

 ing structures, namely, of linin, nuclear wall, and cyto- 

 plasmic reticulum. No centrosome is present, nor could 

 any special spindle-forming substance be recognized. 



Botanical Laboratory, 



University of California, 

 Berkeley, California, 

 May I, 1898. 



