346 CALIFORlSnA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



In regard to the granular zone, which is so prominent in 

 Cassia, little remains to be said. This zone has been de- 

 scribed and figured for several plants such as Hemerocallis 

 (Juel,i897) , Larix^Eqiiisetum, Lilium, Passiflora^Lavaiera, 

 Cobcea, Gladiolus, Podophyllum SLnd Helleborus (the last two 

 by Mottier, 1897a) but always in reproductive cells at the 

 time of division, and not in vegetative cells at the same 

 stage. The partial disappearance of the granules during 

 the formation of the fibrous zone seems to indicate that they 

 are an accumulation of material ready for immediate use. 

 The large quantity present in reproductive cells which 

 divide twice in rapid succession points to the same thing. 

 And though the granular zone is present even in the last 

 stages of the second division, though not always so promi- 

 nently (Lawson, 1898, p. 178), and in fact after the pollen- 

 grains have separated (Byxbee 1900, fig. 25), it must be 

 remembered that a large quantity of food material is needed 

 within a comparatively short time of activity, not only by 

 the pollen-mother-cell but also by the pollen-grain. As 

 Byxbee (1900, p. 72) points out, the manner in which the 

 granular zone accumulates, suggests the gathering of deuto- 

 plasm in animal eggs (Wilson, 1896, p. 115 et seq.). 



Summary. 



1. The cytoplasm of the young pollen-mother-cell is 

 made up of a network of more or less radially arranged 

 fibers, upon and between which larger and smaller granules 

 are found (fig. i). 



2. The spindle is formed as follows: 



a. The meshes adjacent to the nuclear wall be- 

 come smaller, and elongated parallel to the 

 nuclear wall (fig. 2). 



b. A granular zone accumulates around the 

 nucleus. In the cytoplasm, especially in the 

 peripheral part, appear deeply-staining rough 

 fibers, frequently arranged in conical groups 



(fig- 3)- 



