108 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



/ 



One other possible stage in the life-history of S. antarctica has been observed 

 (PI. I., fig. 17). This consists of a delicate, more or less oval membrane surrounding 

 four oblong individuals of irregular shape, in some of which a pyrenoid was discernible ; 

 the irregular shape is due to the formation of various outgrowths on the surface of 

 each individual. I have rather tentatively regarded these four cells as Scotiella-cells 

 in the making, the outgrowths, which appear to be solid, being interpreted as the 

 developing wings. Only two such stages have been observed, and they were both in 

 the same condition, so that future observations must show whether the above inter- 

 pretation is correct. Certainly no great stretch of the imagination is necessary to 

 derive an ordinary Scotiella-individual from the oblong cells seen in fig. 17. If these 

 stages really belong to the Scotiella, we still require to know whether they represent 

 the division of an ordinary individual or of a resting-cell. 



We may next proceed to consider the systematic position of Scotiella. In view 

 of our rather incomplete knowledge of the organism, its affinities are not easy to 

 determine, but I am inclined to regard it as a fairly close ally of the genus Oocystis, 

 from which it differs chiefly in its characteristic wings, and in the marked storage of 

 fat. Should fig. 17 actually represent a reproductive stage of an ordinary individual 

 of S. antarctica, then the latter organism would reproduce in a very similar way to 

 Oocystis. The cells of the latter are described l as having one or more parietal chloro- 

 plasts with or without pyrenoids ; so that the probable occurrence of a single chloroplast 

 with a pyrenoid in the Scotiella does not speak against a relationship with Oocystis. 

 The latter genus is included by Oltmanns 2 in his Scenedesmacese, while Wille refers 

 it to the OocystaceaB. 3 



Before concluding the discussion of S. antarctica, reference must be made to the 

 fact that the resting-cells (fig. 15) above referred to this species show considerable 

 resemblance to Trochiscia insignis (Reinsch), Hansg. ( = Acanthococcus plicatus, 

 Reinsch), and to T. obtusa (Reinsch), Hansg. ( = A. obtusus, Reinsch).* In the former 

 case the cells are much larger than the resting-stages ascribed to the Scotiella, but in 

 the latter case the dimensions approximately agree. It would, however, be inadvisable 

 at the present moment to attempt any further comparison between these forms. 



(d) SCOTIELLA POLYPTERA, n. sp. (PI. I., figs. 18-21). 



The second species of Scotiella, S. polyptera, 6 n. sp., was, as above stated, only 

 rarely found in the yellow snow material, but rather more abundantly in samples 1 1 

 and 15, from which all the figures were drawn (PI. L, figs. 18-21). The material 

 of this species was, however, so scanty, and the state of preservation of the 



' Of. Wille, loc. cit., p. 58. 



2 Oltmanns, Morph. u. Biol. d. Algen, vol. i., Jena, 1904, p. 183 et eq. 



8 A full diagnosis of the new genus and species, with measurements, will be found on p. 125. 

 * Of. Migula, Kryptogamenfl. v. Deuttchland, Deutsch.-Osterreich . d. Sckwiz, ii. 1, p. 634, and pi. 35, E, fig. 5, 

 pi. 35, r, fig. 10. 



6 iroxiij, many ; rrtpbv, a wing. 



