iQoS] YAMANOUCHI—SPOROGENESIS IN NEPHRODIUM 17 



spheres arise before cell plates are laid down betweei 

 he protoplast of the spore mother cell in this ca-c be 

 simultaneously into four tetrahedral spores. 



Discussion of cytological phenomena 



Nuclear reticulum:. — Since the terms "chromatin" and *'linin" 

 were given by Flemaiixg (21) and by Schwarz (42) respectively to 

 the substance of the nuclear network which stains deeply and to the 

 substance of the achromatic reticulum, these two substances have 

 been resrarded as essential constituents of the nucleus in its resting 



stage, and it became 



fine 



imbedded chromatin granules 



and 



^b^ 



and differentiation of these two elements needs special 



mv 



between the telophase 



prophas 



notion regarding the nature of chromatin and linrn, similar to 

 the conclusion drawTi by Gregoire and Wygaerts (25). 



WTien a group of daughter chromosomes reaches the pole, they 

 are first dra^\Ti tightly together, so as to lose, apparently, their indi\ad- 

 ual outlines. Vacuolization then takes place in this mass, and with 

 the appearance of vacuoles parts of the mass of chromatin substance 

 become irregularly separated and distributed so as to become trans- 

 formed into a ragged reticular structure consistmg of anastomosing, 



gular clumps and finer, branched strands 



membrane 



may be formed by the contact of the surrounding c>-toplasm with 

 the nuclear sap that appears in the vacuoles, separates the mass of 

 chromatin substance from the c}-toplasm outside at a ver}' early period, 

 so that it is highly probable that no achromatic structures are included 

 within the nucleus. The nuclear reticulum of the resting stage is 



the 



'o 



pirem of the ensuing division is formed again by the 



arrangement of the r^ged chromatin reticulum 



seems 



lum is derived entirely from the chromosomes 



