COLLECTED IN THE SOUTH ORKNEYS. 313 
cells he describes with Chloromonas alpina is a little doubtful, it may be that 
the latter constitute a second species of Chodatella occurring in tne snow 
flora. 
(gy) OocvsrIs LACUSTRIS, Chod., f. NIVALIS, F. E. Fritsch. 
(PI. 10. figs. 27, 28.) 
Side by side with Chodatella brevispina, but much rarer than the latter, 
there occurs another form, which shows many similarities (Pl. 10. figs. 27, 
28). The cells are of the same general shape and the cell-contents are often 
quite identical, there being two terminal globules of fat with intermediate 
granular protoplasm (fig. 27) ; a pyrenoid could not be made out. These 
cells, however, differ from those of Chodatella brevispina in three prominent 
respects : they are always of smaller dimensions (length 13-15 иш), they have 
a perfectly smooth rather thin membrane devoid of spines, and the ends are 
commonly more or less pointed (fig. 27) and never rounded off to such 
а marked extent as is the case in Chodatella brevispina (ср. even fig. 28 with 
figs. 25, 26). Were it not for the difference of shape and the absence of all 
intermediate stages these cells might be regarded as young individuals of the 
Chodatella, but as it is this view is scarcely permissible. Similar cells, though 
somewhat larger, appear to have been observed by Lagerheim * in red 
snow from Mt. Pichincha in Ecuador ; he suggests that they may belong to 
some member of the Volvocinex. It seems much more likely, however, that 
they represent a species of Ooecystis. In one or two cases a considerable 
number (about 16) of these cells were observed lying within a common 
mucilaginous investment, which would point to some species like Oocystis 
lacustris ог O. glvocystiformis. There are further resemblances to O. lacustris 
in the pointed shape of the cell, in the (probably ?) single chloroplast, and in 
the occurrence of oil-drops in the latter species f ; also in the very feeble 
thickening of the ends of the cells of O. lacustris $, a feature which is much 
more pronounced in other species of the genus. For these reasons I am in- 
clined to regard the cells shown in figs. 27 & 28 as merely a form (nivalis) of 
Oocystis lacustris, Chod., characterized by the prominent storage of fat $; the 
cells which Lagerheim observed may possibly belong to the same species. 
* Lagerheim, * Schneeflora des Pichincha," in Ber. Deutsch. Bot. Ges. x. 1892, p. 525, 
footnote *.—“ Zahlreiche ovale Zellen, 6-10 д dick und 10-20 и lang, welche grünen Inhalt 
und an den Enden je einen zuweilen róthliehen Oeltropfen führten. Sie lagen immer isoliert 
und konnten nicht zur Entwickelung gebracht werden." 
+ Cf. Chodat, “ Études de Biologie lacustre, in Bull. Herbier Boissier, v. 1897, p. 296 ; 
also ‘ Algues vertes de la Suisse,’ 1902, p. 190, fig. 105. 
{ Chodat’s figures in most cases give very little indication of this thickening, which was 
not to be found in the Antarctic specimens. The latter may possibly have been relatively 
voung individuals, a view which is supported by the thinness of the walls, 
$ See also p. 326. 
Z2 
