Notes . 
4i3 
certainly determined. There seems reason to believe that various 
characters in Oedogonium , which have received different interpreta- 
tions by different authors, are really distinct, according to the species 
examined. This certainly appears to be the case with regard to the 
first division of the young plant. 
I have examined the germination of the zoospores in Oed. capillare , 
Kiitz., a species in which the end cell of the filaments bears a distinct 
tip 1 . During its active movement the zoospore has a nearly spherical 
form, but on the cessation of activity it acquires an oblong elongated 
shape (Fig. 23, a). Immediately after coming to rest, a strip of thick, 
whitish membrane begins to make its appearance at the end opposite 
to that which bore the cilia. This becomes gradually more and more 
distinct, whilst at the same time a delicate membrane is formed round 
the rest of the zoospore (Fig. 23, a). Soon after the thick portion of 
the membrane (which marks the anterior end of the new individual), 
undergoes, as it appears, mucilaginous degeneration, for shortly a clear 
space containing mucilage is to be found at this point, bounded 
towards the exterior by the thin membrane, which surrounds the 
whole zoospore. Thereupon this colourless portion grows out to 
form a short hollow tip 2 3 (Fig. 23, b). When this has reached a slight 
development, we see a similar strip of thickened membrane formed at 
the opposite, posterior end of the embryo (Fig. 23, b). Just as at the 
anterior end this is disorganized, leaving a well-marked clear space 
behind (Fig. 23, c), which grows out to form the root of the new 
individual (Fig. 23, d). In the case described, the root after growing 
for some time divided at the apex into two rootlets, which continued 
to grow separately and apically. I was unable to figure the whole 
course of the development in a single individual, so that the stages in 
Fig. 23, a-d , are from different plants. 
It is noteworthy that the tip practically always commences its 
development before the root. It is not uncommon to find a young 
plant with an almost fully-developed tip, whereas the root is scarcely 
developed. The time in which the tip develops seems to vary very 
much, from 2-24 hours; probably from 3-4 hours is the normal 
1 A number of species of Oedogonium are provided with a tip like that of 
Oed. capillare ; thus Wolle (Freshwater Algae of the United States, 1887) figures 
the young plants of Oed. autumnale (PI. 81, Figs. 4 and 5), which bear a very 
distinct tip : cf. also Oed. crispum , var. rostellatum (PI. 74, Figs. 12 and 13). 
3 Later on this tip becomes solid (cf. Fig. 23,/i) 
