COLLECTED IN THE SOUTH ORKNEYs. 331 
Figs. 7-11. Scotiella antarctica, V. Е. Fritsch. 1-2=principal wings; 3-4 and 5-6 = (Пе two 
pairs of lateral wings; рас = principal wings. Fig. 7. А rather small normal 
individual, as seen when the principal wings are parallel to the substratum 
(x 830). Figs. 8, 9. Two oblique end-views of the orgauism to show the course 
of the wings (x830). Fig. 10. Part of a normal individual in which the 
principal wings are inclined to the substratum (X540). Fig. 11. An individual 
seen in optical section ( x 430). 
Figs. 12-16. Scotiella antarctica, F. E. Fritsch. Stages in formation of resting-spores (7). 
Fig. 12. An individual in which the wings have lost in definition ( X 540). 
Figs. 13, 14,15. Three stages in the production of the resting-cell (X540). 
Fig. 16. An early stage in the formation of a resting-cell ; contents rounded off 
and wings irregular ( x 410). 
Fig. 17. Scotiella antarctica, Е. E. Fritsch. А possible stage in the produetion of four new 
individuals ( x 1100). 
Figs. 13-21. Scotiella polyptera, Е. E. Fritsch. Fig. 13. An individual seen from the side, 
showing the numerous undulated wings ; contents not figured (x 1100). 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 (x1100). Fig. 21. А 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.), Chodat. Three individuals, showing the 
course of the wings and the contracted contents. (x 850.) 
Figs. 95-26. Chodatella brevispina, F. E. Fritsch. Two individuals showing different 
methods of distribution of the fat. (х 880.) 
Figs, 97-28. Oocystis lacustris, Chodat, f. nivalis. Two isolated cells from the yellow snow. 
(х 880.) 
Fig. 29. Trochiscia nivalis, Lagerh. (x 1100.) 
Fig. 30. " antarctica, Е. E. Fritsch, from the yellow snow. (х 1100.) 
Fig. 31. Pteromonas nivalis (Shuttelw.), Chodat? (х1 100.) 
Figs. 32-33. Raphidonema nivale, Lagerh. (х 890.) 
Vig. 34. Haphidium pyrenogerum, Chodat ? (х1100.) 
Figs. 35-40, Chlamydomonas caudata, Wille. Figs. 35, 30. Subdivision of the cell-contents 
(х 650). Figs. 87, 38. Two normal individuals (x750), Fig. 39. Individual 
with a very strongly thickened posterior tip (X 190). Fig. 40, Front end of an 
individual to show a prominent beak between the two cilia ( x 880), 
Puate 1l. 
(All the photographs * on this Plate are representations of stained material of yellow 
snow at various magnifications. The following symbols are used: C= Chlorosphera 
antarctica, Е. E. Fritsch; Ch= Chodatella brevispina, F. E. Fritsch; P— Protoderma ant- 
arctica, F. E. Fritsch; S= Spherocystis Schröteri, Chodat; Se= Scotiella antarctica, F. E 
* 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. Iam much indebted to my friend Mr. E. Hatschek for assistance 
in taking the photographs. 
