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 antardica, n. sp. A possible stage in the production of four new individuals 



(xllOO). 



Figs. 18-21. Scotiella 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 side, 

 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. Ghotlatella brevispina, n. sp. Two individuals showing different methods of distribution 

 of the fat ( x 830). 



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



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



Fig. 30. ,, antardica, 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. RaplMiwn 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 1 on this plate are representations of stained material of yellow snow at various 

 magnifications. The following symbols are used: 0= CMorosphaera antardica, F. E. Fritsch; Ch = Chodatella 

 brevispina, F. E. Fritsch; P = Protoderma brownii, F. E. Fritsch ; S = Sphxrocystis schroeieri, Chod., f. nira/ix ; 

 Sc = Scotiella antardica, F. E. Fritsch; U=Ulofhrix. (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 tlie 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 

 Chlorospltfera-ceUs, together with three individuals of Scotiella antardica. Short filaments of Ulotlirix 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 SphaToryxlix at the upper end, and an older colony 

 towards the base. Chlorosphsera-celh 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 Cltlorosp/inera-c&lls, 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 antardica, 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 Cliodateila 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 Scntiella, a number of Chlorosph(vra-cel\$, and Ulotlirix-fil&ments are visible, while the 

 ground-mass consists of Prtitoderma. 



1 The photographs on this plate were made with the help of a pliotomicrographic 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. 



