481 
the young plants in Oedogonium . 
the plant. Oedogonium is one of the hardiest genera of fresh- 
water Algae, and it is likely that unsuitable conditions would 
take a long time to put an end to its vital activity, unless 
they were extremely fatal in their action. As a matter 
of fact, if cultivated in very strong solutions of cane-sugar 
the above-described appearance can be called forth in a few 
days, and, although then returned to fresh water, not a single 
filament becomes green and active again. 
A glass vessel in the Herbaceous Department contains 
a mass of Oed. capillare^ which has been in this condition 
for some months, and I do not think is likely to recover. 
I first noticed a change in the filaments in March of this year. 
I then found that the (still green) contents of the cells were 
aggregated chiefly about the transverse walls, and sometimes 
so closely that these could only be recognized on a close 
perusal. The side-walls also were lined by a thin layer, but 
the whole interior of the cells was either quite empty or only 
contained a few strands of protoplasm. At the time of writing 
all the cells are absolutely colourless and many are crowded 
with starch-grains ; the arrangement of the protoplasm, how- 
ever, indicates that most are still living. As to the external 
conditions, which cause this change, I can say nothing ; Nitella 
syncarpa growing in the same water is perfectly healthy, but 
some Closteria present are in a similar state of degeneration. 
4. Abnormal Formation of Zoospores and 
their Development. 
The adult filaments of Oedogonium almost invariably form 
zoospores after being kept in a slow stream of water (Zimmer- 
mann, * 92 , p. 3) for some time 1 . The emission of the zoospores 
takes place very abundantly for some days, but then as bacteria 
gradually collect in the cultures and the filaments of the Oedo- 
gonium itself become exhausted, the process slackens down 
again 2 . Under these final (abnormal) conditions the zoo- 
spores formed often present curious characters (Fig. 27, e.fg). 
1 These experiments were carried on during the months January to June, 1902. 
2 Fritsch, ’02, p. 415. 
