Cytology of Polyphagtis Euglenae. 187 
again into larger drops. This went on rapidly, so that by 3 o’clock the 
contents of the sporangium had quite a different appearance (Fig. 15). 
These larger drops then run together in twos and threes (Fig. 16), and 
at 4 p.m. these groups had fused together to form a number of oil-drops 
nearly equal in size and fairly equally spaced (Fig. 17). 
At this stage the segregation of the zoospores begins. The granular 
protoplasm containing yellowish oil-drops of different sizes becomes aggre- 
gated into masses separated by delicate lines of cleavage (Fig. 18). 1 These 
spore-origins may be as shown in Fig. 1 8, or they may be more irregular in 
size and shape, as shown in Fig. 22, and the lines of demarcation may dis- 
appear and reappear again. Very soon, however, the spore-origins contract 
slightly and become clearly marked off from one another. At about this 
stage a movement of rotation becomes visible in the sporangium and the 
spore-origins appear to move slowly over one another. This is probably 
due to the gradual rotation of the whole protoplasmic contents of the 
sporangium, as described by Hartog (’ 87 , ’88) in species of Saprolegnia. In 
a few minutes the lines of demarcation become invisible and the spore- 
origins seem to fuse. The explanation to be offered of this apparent fusion 
is probably that the cleavage of the protoplasm begins in the centre of the 
sporangium and gradually extends towards the periphery. At the moment 
when the lines of cleavage reach the periphery and the outer layer of the 
cytoplasm is ruptured, thus completely separating the spores, there is 
a loss of turgescence and consequent contraction in the sporangium, and it 
is this, and possibly a swelling of the young spores also, which brings about 
the apparent fusion of the spores (cf. Hartog, ’ 87 , ’88, and Rothert, ’ 87 ). 
For a short time the lines of cleavage remained invisible ; the oil-drops 
underwent further fusion, and at 5 p.m. were observed to be moving slowly 
backwards and forwards. At 5.45 p.m. fine lines again appeared dividing 
the protoplasm into smaller polygonal masses, each of which contained one 
oil-drop, and at 6 p.m. these protoplasmic masses had become completely 
separated from one another although still compressed into a polygonal 
shape (Fig. 19), but they at once commenced to move slowly, and at 
6.5 p.m. were observed to elongate (Fig. 20) and take on the form of 
ripe spores. The oil-drop was now at one end of the spore. At 6.8 p.m. 
the apical portion of the sporangium wall gradually became thinner, 
and finally an opening was formed and the zoospores came out 
(Fig. 21). As they come out they swim away, but some of them have 
their cilia entangled among those still in the sporangium and are seen 
at the opening of the sporangium for some time making short jerky move- 
ments, apparently trying to tug their cilia away. After a little time they 
1 This stage and those which follow are very interesting, and show slight variations in different 
sporangia. Thus Figs. 22 to 25 are from an asexual sporangium, in which 64 spores were produced, 
and may be compared with the same stages of the smaller sexual sporangium in which there were only 
32. As a rule, the apparent fusion of the spore-origins is more pronounced in the larger sporangia. 
