342 BOTANICAL GAZETTE [MAY 
The primary sporogenous cell—At the same time the primary 
sporogenous cell is undergoing important changes. It increases 
very much in size, its contents becoming less and less dense, 
until in some cases vacuoles make their appearance (jig. 6). 
The nucleus also increases in size, and is often surrounded 
by an area of hyaline cytoplasm (kinoplasm), while radiating 
strands of granular protoplasm extend from the nucleolus to the 
periphery of nucleus (figs. 2, 3). The chromatin of the nucleus 
now collects in a closely compacted mass, with a dense non- 
granular nucleolus by its side (figs. 4, 5, 6), the cell having 
passed into the synapsis stage so characteristic of mother 
cells. 
That the development of the primary sporogenous cell has 
been simultaneous with the formation of tapetal tissue is shown 
by the fact that in many cases the former cell has been found in 
early synapsis with only a two-layered tapetum (fig. 4). As the 
nucleus of the mother cell passes to the spirem stage, the chro- 
matin threads are usually more on one side than on the other. 
The nucleoli never appeared granular, though often one to several 
very large granules or black grains could be seen. The cyto- 
plasm was never uniform in appearance, at times having a retic- 
ulated appearance (fig. 5), and again a stringy appearance 
Fig. 6). 
It may be stated that if the manipulation of the stains has 
been fortunate, one finds in all phases of synapsis an excellent 
illustration of the value of cyanin and erythrosin as differential 
stains, the chromatin being always a deep red and the nucleolus 
a deep blue. There was in the case of Potamogeton no differ- 
ence in the way in which the stains were taken up by nuclei of 
the megaspore and microspore mother cells, thousands of the 
latter showing the highly erythrophilous chromatin and the 
highly cyanophilous nucleoli seen in the former. 
Development of potential megaspores.—\t was some time before 
any positive evidence of an axial row could be found; but the 
presence of a cap of densely staining protoplasm at the micro- 
pylar end of the sac was a strong indication of its presence. 

