134 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



production of the resting-cell ( x 540). Fig. 16. An early stage in the formation of a resting-cell ; contents 

 rounded off and wings irregular ( x 410). 



Fig. 17. .Scotiella antarctica, n. sp. A possible stage in the production of four new individuals 

 (xllOO). 



Figs. 18-21. Scotidla polyptera, n. sp. Fig. 18. An individual seen from the side, showing the 

 numerous undulated wings ; contents not figured (xllOO). Fig. 19. Production of four new individuals; 

 wings on mother-cell indistinct, but showing the spiral trend ( x 1500). Fig. 20. Oblique end-view of an 

 individual to show the course of the wings ( x 1100). Fig. 21. A normal individual seen from the sidei 

 showing the shrunken cell-contents, the spiral wings, and the crenate outline of the whole cell ( x 1100). 



Figs. 22-24. Pteromonas nivalis (Shuttelw.), Chod. Three individuals showing the course of the 

 wings and the contracted contents ( x 830). 



Figs. 25, 26. Chodatella brevispina, n. sp. Two individuals showing different methods of distribution 

 of the fat ( x 830). 



Figs. 27, 28. Ooeystis lacustris, Chod., f . nivalis. Two isolated cells from the yellow snow ( x 830). 



Fig. 29. Trochiscia nivalis, Lagerh. ( x 1100). 



Fig. 30. ,, antarctica, n. sp. From the yellow snow ( x 1100). 



Fig. 31. Pteromonas nivalis (Shuttelw.), Chod.? ( x 1100). 



Figs. 32, 33. Raphidonema nivale, Lagerh. ( x 830). 



Fig. 34. Raphidium pyrenogerum, Chod.? ( x 1100). 



Figs. 35-40. Chlamydomonas caudata, Wille. Figs. 35, 36. Subdivision of the cell-contents ( x 650). 

 Figs. 37, 38. Two normal individuals ( x 750). Fig. 39. Individual with a very strongly thickened posterior 

 tip ( x 750). Fig. 40. Front-end of an individual to show a prominent beak between the two cilia ( x 830). 



PLATE II. 



All the photographs a on this plate are representations of stained material of yellow snow at various 

 magnifications. The following symbols are used: C= Clilorosphtera antarctica, F. E. Fritsch; Ch Chodatella 

 brevispina, F. E. Fritsch; P= Protoderma brownii, F. E. Fritsch ; S= Sphxrocystis schroeteri, Chod., f. nivalis ; 

 Sc = Scotiella antarctica, F. E. Fritsch; U=Ulothrix. (Photographs 1, 2, and 3 are magnified 130 times; 

 photographs 4, 5, and 6 are magnified 400 times.) 



Photographs 1 and 2. Typical views of the yellow snow flora at a low magnification. In the first 

 photograph Protoderma brownii is very predominant, but in the centre is seen a group of fairly large 

 ChlorospJuera-cetts, together with three individuals of Scotiella antarctica. Short filaments of Ulothrix are 

 visible at several points on the photograph. The second photograph shows a very typical stratum of 

 Protoderma near the centre, two young colonies of Sphserocystis at the upper end, and an older colony 

 towards the base. Chlorosphxra-cells of various sizes and often exhibiting well-marked mucilage-sheaths are 

 obvious at many points in the photograph. 



Photograph 3. This shows a very typical group of large CMorosphtera-cells, with well-marked sheaths, 

 together with a thick patch of Protoderma. At the right-hand side of the photograph a number of 

 individuals of Chodatella are to be seen. 



Photograph 4. An individual of Scotiella antarctica, F. E. Fritsch, showing the two principal and two 

 lateral wings. The notch in the right-hand principal wing is very obvious. At the lower end of the 

 individual the two lateral wings can be seen curving inwards. 



Photograph 5. A small part of a Protoderma-sheet highly magnified (only the cell-contents are 

 recognisable) ; this photograph also shows a number of individuals of Chodatella brevispina, F. E. Fritsch. 

 The small spines on the latter are scarcely visible. 



Photograph 6. This shows part of the central group of cells in photograph 1 on an enlarged scale. 

 Three individuals of Scotiella, a number of Chlorosph(era-cel\s, and {/foMriz-filaments are visible, while the 

 ground-mass consists of Protoderma. 



1 The photographs on this plate were made with the help of a photomicrographic apparatus purchased by a 

 research-grant made by the Governors of the East London College, University of London. I am much indebted to 

 my friend Mr E. Hatschek for assistance in taking these photographs. 



