477 
the young plants in Oedogonium. 
besitzen wie alle Zoosporen sogar zwei Membranen. . . . Die 
innere Haut der Zoospore hat wachsend die aussere Haut der 
Zoospore schon vor ihrem Austritt aus der Vegetationszelle 
so durchbrochen, wie die Tochterzelle die Mutterzelle bei der 
Theilung durchbricht, dadurch entsteht die Offnung der 
ausseren Haut ; dieses Verhaltniss ist an der keimenden Spore 
nachweisbar, wo jedesmal die Offnung der ausseren Sporen- 
haut sichtbar wird, und zugleich auch die an ihr befestigten 
Cilien noch spater wenigstens in Rudimenten gefunden werden 
konnen.’ On PL IV, Figs. 36-31, he figures the development of 
the young plant, exhibiting this collar round the upper part 
of the root-end (cf. also Hartig, ’55, p. 415). I have observed 
nothing of this nature in my cultures. 
Wolle (’87) figures on Plate LXXIV, Figs. 12 and 13, one 
and eight-celled plants of Oed. crispum , var. rostellatum y both 
with an attaching-disc and a distinct tip. On Plate LXXXI, 
Figs. 4 and 5, a unicellular plant of Oed. autumnale with a 
long rhizoid and another with an attaching-disc is shown. 
This is not intended to be by any means a comprehensive 
discussion of the literature involved. I have merely mentioned 
those observations which seemed to me of interest in con- 
nexion with the species discussed above. 
2. The first Cell-division in the Young Plant. 
I have already discussed (cf. Fritsch, 1902) the first cell- 
division in connexion with Poulsen’s 1 observation that the first 
cap of the young plant is cast off. At the time I had not yet 
observed this phenomenon, although I had carefully investi- 
gated this point in three species 2 . Since then I have seen the 
casting-off of the first cap in a number of species, and have 
found that, although fairly constant for some, in others the 
cap is just as often retained. Thus in Oed. cardiacum the 
casting-off of the first cap is the rule ( v in fig. 26, c and 27, a ), 
nearly all the two-celled plants showing the cap still in 
1 Poulsen, ’ 79 , p. 1, &c. ; cf. also Hartig, ’ 55 , p. 417; Tab. IV, Figs. 12, 
13 and 14. 
2 Namely, Oed. capillare , the species from the river Severn, and another unde- 
termined species. 
