148 . BOTANICAL GAZETTE [FEBRUARY 
strand of cytoplasm (fig. 31,a@). The spores seem to round off soon 
after their membranes are laid down, presenting as they do so 
somewhat the appearance of bodies being divided by advancing 
cleavage furrows. Observation of the terminal portions of the 
apparent furrows shows, however, that they merely separate spore 
membranes already formed by precipitation within the cytoplasm. 
This is made especially clear at the angles of the protospores, 
where the membranes frequently cut across the corners, leaving 
small portions of the cytoplasm which do not enter into the 
formation of any spore (fig. 31,0). 
MATURATION OF ZOOSPORES.—Although the protospores quickly 
round off and separate from each other, they remain in the position 
occupied before segmentation. Consequently the mass of young 
spores retains the shape of the coenocyte from which it was derived, 
leaving the central vacuole unoccupied as before segmentation, as 
in fig. 28, which shows the condition of the great majority of the 
segmented cysts observed. In such sporangia the young spores 
are usually regular ovoid cells (fig. 33), without the differentiation 
of parts characteristic of the mature spore. Only rarely were 
fully matured zoospores which had moved out into the cavity of 
the cyst found in the sections studied. In such ripened spores there 
is a conspicuous differentiation into anterior and posterior ends 
(figs. 35, 36). In the posterior end is collected the larger part 
of the cytoplasm with the starch grains, if any be present, while 
the anterior end appears highly vacuolate in fixed preparations on 
account of the removal of the pigment which occupied it during life. 
In no case was I able to assure myself that cilia were present 
in the section studied, although I thought I saw them several 
times. This was probably due to imperfect fixation, since the 
chromacetic acid used is not as well adapted for preserving such 
structures as some killing fluids which might have been used had 
it been possible to experiment on the ground. In zoospores fixed 
in osmic fumes, after liberation the cilia were of course clearly 
shown (fig. 37), and in these, as well as in many of those on the 
sections (fig. 36), there was a conspicuous deeply staining body at 
the base of the cilia such as has been found in zoospores of many 
other forms. In many of the spores, especially those a little over- 
