480 Fritsch . — The Structure and Development of 
oogonium, it would differ from a dwarf-male only in size and 
development of the vegetative structure, due to its origin from 
a normal, chlorophyll-bearing zoospore. 
Another interesting abnormality is shown in Fig. 27, a . 
This young plant was derived from a zoospore of Oed. car - 
diacum y which was being grown in a 2 per cent, solution of 
cane-sugar, in order to further the formation of oogonia 1 . 
Although the conditions were unfavourable to the formation 
of much protoplasm and consequently to the growth and 
division of the plant, it was able to form large amounts of 
cellulose, which resulted in the formation of successive rings 
{c 1 , c 2 , c 3 ). The first ring had been of the kind mentioned 
above and after its formation the plant must have stretched 
itself, for there is the usual cap (v) loosely covering the apex 
of the cell. The following rings (c 3 , c 2 , c 1 ) were then succes- 
sively formed without any further stretching of the cell taking 
place. Several such cases were observed in the sugar solution, 
the upper part of the cell presenting a truly elegant design. 
Finally, 1 wish to make mention of a curious condition of 
the young plants, observed chiefly in Oed. calcareum and 
capillare , but also to a less extent in one or two other species. 
The former species had been kept in a glass vessel in the 
laboratory a month or so, and numerous zoospores had come 
to rest and germinated on the sides of the vessel. In the 
young plants thus formed only the basal cells contained 
chlorophyll, those higher up being filled with starch grains. 
The cells of these plants were considerably elongated, narrowing 
down more and more the further they were situated away 
from the base, the cells at the apex being often not more 
than a quarter of the diameter of the basal cell ; so that the 
plants looked as though they narrowed down into a hair 
apically, especially as the uppermost cells had generally almost 
lost their contents. Such a condition of Oedogonium has 
been recently described in America (Keller, 1901), and inter- 
preted as a kind of resting-stage. I do not think this very 
probable, and rather look upon it as a gradual dying-off of 
1 Cf. Klebs, ’ 96 , pp. 279, 280, 
