112 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



daughter-individuals, which often acquire the shape, spines, etc., characteristic of the 

 mature form before leaving the mother-cell (autospore-development). The individuals 

 of Chodatclla brevispina were frequently found lying together in groups of four or more, 

 and that may indicate formation from a common mother-individual, but no stages in the 

 process were observed. In most other species of Chodatella the spines are very long, 

 few in number, and mostly confined to the two ends of the cell ; but there are two 

 species (viz. C. echidna (Bohlin), Chod., and especially C. armata, Lemm.) 1 in which 

 the spines are more evenly distributed and also of approximately equal length. No 

 other species of Chodatella, however, bears spines all over its surface. In all the 

 described species tbe spines are very much longer than in the Antarctic form, and for 

 this reason the specific name " brevispina " is proposed for the latter. In his description 

 of C. cihata (Lagerh.), Lemm., Choclat 2 states that the cells are "souvent munies de 

 quelques globules huileux polaires," so that the occurrence of fat has already been 

 recorded in the genus. The species of Chodatella, lastly, have one (or more) chloroplasts 

 with or without pyrenoids. On the whole, therefore, the Antarctic form fits fairly well 

 into the genus Chodatella, and owing to its numerous short spines and abundant storage 

 of fat is regarded as a distinct species. 3 



Before passing on to the consideration of other forms it may be well to point out 

 that there is some resemblance between Chodatella brevispina and the aplanospores of 

 Chlorornonas alpina, Wille/ found by Wille in green snow in Norway. Wille himself 5 

 refers to the resemblance of these aplanospores to Lagcrheimia (a closely allied genus, 

 regarded by many authorities as not generically distinct from CJiodatella), but found 

 transitions seeming to connect these structures with the ordinary motile cells of C. alpina. 

 As regards the resemblance between C. brevispina and these aplanospores (apart from 

 similarity in shape and size), it is purely superficial ; for the latter have coarse pointed 

 spines attached to the cell-wall by a broad base, they contain many plano-convex chloro- 

 plasts, and, although occurring in the same kind of habitat (on snow), appear to harbour 

 no fat. If Wille's interpretation of these structures is correct, there is a possibility of 

 the individuals of C. brevispina being aplanospores of some allied form ; inasmuch, 

 however, as Wille's evidence for the connection of the spiny cells he describes with 

 C. alpina is a little doubtful, it may be that the latter constitute a second species of 

 Chodatclla occurring in the snow flora. 



o 



((/) OOCYSTIS LACUSTRIS, Chod., f. nivalis, n. f. (PI. I., figs. 27, 28). 



Side by side with Chodatella brevispina, but much rarer than the latter, there occurs 

 another form, which shows many similarities (PI. I., figs. 27, 28). The cells are of the 



1 Choclat, loc. cit., p. 192 ; Migula, loc. cit., p. 671, pi. 35, Q, fig. 6. As the Antarctic species is not a plankton- 

 organism like most other species of the genus, the relative shortness of tLe spines is comprehensible. 



2 Loc. cit., p. 192. 



3 A full diagnosis of Gltodatella brevispina will be found on p. 124. 



4 C/. Wille, " Algologische Notizen, xi.," Nyt Maiju^i/i f. \ntui-i-iili ttxbili, xli., 19<>3, p. 124, and pi. iii., figs. 32-33. 

 '> Loc. cit., p. 124. 



