COLLECTED IN THE SOUTH ORKNEYS. 307 
also 16) ; in such eases some or all of the wings appear irregularly folded 
and stratified, so that they no longer show up so markedly (cf. figs. 12 & 16). 
Various stages of this kind have been found, which seem to form a complete 
series connecting the normal Scotiella-individual with large thick-walled 
resting-cells (fig. 15), the general shape of which is rounded, while the 
membrane is double with a more or less undulated outer layer. The forma- 
tion of these resting-cells (akinetes) appears to be initiated by a swelling-up 
of the wall of the individual and the rounding-off of its contents. Asa 
result of the swelling of the wall the outline of the wings is obscured, while 
the wall becomes more or less rounded off around the contracted contents 
(cf. figs. 13, 14) ; at the same time a stratification shows itself in the 
swollen wall, which subsequently grows more strongly and markedly 
thiekened (figs. 14, 15). The contents appear to undergo a. gradual change 
during the formation of the resting-cells. At first (fig. 13), as in the 
ordinary individuals, we have a central mass of. granular protoplasm with a 
cap of fat at either end ; as the contents round off, however, this fat disappears 
(used in forming the thick wall?), and the mature resting-cell contains only 
granular protoplasm (fig. 15)—possibly with a certain amount of fat diffused 
through it. Resting-cells of the type just described are fairly common in 
parts of the yellow snow material, but I have not met with any structures 
which could be i interpreted as germination-stages of these cells ; their further 
fate must therefore at present remain an open question. 
One other possible stage in the life-history of Seotiella antarctica has been 
observed (Pl. 10. 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 Scotiedla-cells in the making, the 
outgrowths whieh 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 
interpretation 15 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 беоне Ца. In 
view of ourrather 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 repro- 
ductive stage of an ordinary individual of Scotiella antarctica, then the latter 
organism would reproduce in a very similar way to Ooeystis. The cells 
