46 
The Ohio Naturalist. 
[Vol. X, No. 3, 
In almost every cell in which there are several of these 
amoebulae they may be seen to become associated in pairs, 
(Fig. 4), coming into closer and closer contact until the plasma 
membrane between them breaks down and the cvtoplasm 
of the two fuses (Figs. 5, 6). All stages in this conjugation 
except the disappearance of the plasma membrane are very 
easy to observe, many dozen of them being found in mv 
slides. The nuclei, however, do not fuse though they may in 
the early stages lie close together. Immediately after conjuga- 
tion which seems to take place soon after the amoebulae have 
entered their host, growth begins and seems to proceed rather 
rapidly judging from the fact that conjugating forms are much 
more abundant than such stages as are shown in Figs. 8 and 9, which 
immediately follow. Without any further change in structure 
the zygote continues to grow until it has completed its active life 
when it encysts and becomes a binucleate resting spore. 
Though there are frequently two or even more than two 
zygotes in a single cell all of the amoebulae do not succeed in 
conjugating. Such as fail become large coenocvtes which ulti- 
mately segment into zoosporangia. The very early stages in the 
division of the nuclei of these zoosporangia are so minute and 
difficult to follow that one can hardly be certain of the correctness 
of his conclusions. But apparently the nucleus fragments by 
constriction into about four daughter nuclei while the parasite is 
yet very small (Fig. 13, a). These do not further subdivide until 
a considerable enlargement both in nuclei and cytoplasm of the 
parasite has taken place. (Fig. 13, b). Such quadrinucleate 
parasites are fairly abundant and from this stage on the course 
of development is easy to follow. The parasite increases from 
10-15/z, usually to about 70 /t and the nuclei multiply until they 
become exceedingly numerous and very minute (Figs. 14 4 7). 
No spindles were observed at any time in this process of multi- 
plication, while some clear cases of amitosis were seen (Fig. 14). 
The nuclei are so minute however, that it cannot be stated pos- 
itively that amitosis is the sole method of nuclear division. At 
the end of this vegetative period the cyst segments into a zoo- 
sporangium (Fig. 18), with an immense number of spores so 
minute (‘2.5 /t) that their finer structure cannot be made out. 
In the intermediate stages of the active cycle both of the 
resting spores and the zoosporangia there is a strong tendency for 
the vacuoles of the cvtoplasm to coalesce to form one large cen- 
tral vacuole (Figs. 14-17), traversed only by very fine strands of 
cvtoplasm. This central vacuole may appear very early (Fig. 14) 
or it may not appear at all (Figs. 9-13). During these stages also 
refringement deeply staining granules frequently appear on the 
strands of cytoplasm (Figs. 11, 16). These resemble closely the 
