416 
Notes. 
Fig. 23. Oedogonium capil- 
lar e, Kiitz. a, b, c, d. Stages 
in the development of the 
zoospores : e. The young, uni- 
cellular plant has liberated its 
contents, the upper part of the 
cell-wall forming a kind of lid. 
f A young, two-celled plant 
with a well-developed basal 
disc. (All Figs, x 375-) 
watch-glass-shaped cap (Figs. 9, 10, 11, 
13, 4), which consists of cuticula and 
the outermost of the above-mentioned 
secondary layers ' (p. 6). Through the 
aperture thus formed, the contents pro- 
trude, bounded apically by the inner 
(elastic) secondary membrane mentioned 
above. After this new membrane has 
been considerably stretched by the grow- 
ing out of the contents, the first trans- 
verse-wall appears. The further divisions 
generally took place normally, but in 
some few cases this phenomenon ap- 
peared in a later stage, when the plant 
already consisted of 6-8 cells (p. 7). 
Hirn 1 rather passes over this point, 
merely mentioning that the form of the 
first ring is slightly different from that of 
the succeeding, and that owing to its 
peculiar shape the cap is not infrequently 
cast off. 
I have omitted to follow out the first 
division of the germinating zoospores in 
detail, but I have seen nothing like 
what Poulsen describes and figures. 
Certainly the first cap is not thrown off 
in Oed. capillare , or we should not find 
the tip present on the many-celled young 
plants. All species of Oedogonium, that 
in the older state bear a tip or hair 
apically, probably behave in the same 
manner. But even in other species the 
casting-off of the cap appears by no 
means to be the rule ; in a small (un- 
determined) species from the River 
Severn this is not the case, nor in 
1 Monographic und Iconographie der Oedogoniaceen. Act. Soc. Scient. Fenn., 
tom. XXVII, 1900, p. 15. Wille (loc. cit., pp. 455"6) agrees with Poulsen’s 
description in all essential points. 
