687 
of Terrestrial Algae. II. 
nature—is that in which the granules exhibit an essentially peripheral 
disposition (cf. Fritsch, 1916 , p. 143) ; in such cases they are not un¬ 
commonly rather small and often so densely arranged as to appear like 
a fine moniliform thread in optical section and a coarse pitting in sur¬ 
face view. Granular cells have been observed in all the terrestrial algae 
examined, but are on the whole more striking in the filamentous than 
in the unicellular forms. Nothing of this kind has been seen in the moss 
protonema. 
Particularly when working with strengths of solutions not far above 
the minimum, one often observes a striking correlation between the occur¬ 
rence of plasmolysis and the granular or non-granular character of the 
cell. With these lower strengths it is in the main the non-granular cells or 
those with very few granules that are markedly plasmolysed (cf. Table II), 
and appreciable numbers of granular cells only begin to be strongly plasmo¬ 
lysed when we come to use the higher strengths. This is by no means 
without exception, but nevertheless expresses the general state of affairs. 
Thus, even in relatively weak solutions, one often finds a certain number of 
cells with plentiful granules strongly plasmolysed 1 (cf. Table II). Espe¬ 
cially cells with prominent peripheral distribution of fine granules fail to 
contract until very strong solutions are used, and in Pleurococcus granular 
cells are often the ones to remain unaffected even by a 25 per cent, 
solution of sea-salt. 
Table II. 
Relation of plasmolysis at lower strengths of sea-salt to character 
of cells. 
(a — cells with abundant granules ; b — non-granular cells.) 
Material. 
Exft. 
No. 
Cells 
cozmted. 
Strength 
of sol. 
Strongly 
plasmolysed ,. l 
O/ 
Slightly. 
plasmolysed} 
©/ 
Unaffected. 
O/ 
X 
% 
a 
JO 
b 
/ 
a 
'0 
b 
% 
a b 
Zygogonium 
I 
00 
ON 
1^. 
3 *° 
4*7 
2*1 
28-3 
6-8 
55*3 2*8 
Hormidinm 
II 
423 
3-0 
0-7 
— 
3*8 
33*5 
50-9 
5 -o 
*9 
VI 
2,100 
382 
5 -o 
i*i 
90*6 
5 -o 
i -4 
i-6 
0-3 
Prasiola 
XXVII 
10*0 
— 
7’6 
23-0 
3 1 * 1 
38-2 — 
>> 
M 49 
20’0 
2*2 
72*4 
io*6 
o *4 
14-4 — 
It has, however, become clear that the presence of granules in itself is 
not by any means the sole determinant of the plasmolysing qualities of the 
cells. This has been established by keeping material of the different forms 
investigated well moistened for a fortnight or more, one set being exposed 
to the full light of the greenhouse, the other being screened by a covering 
of slightly translucent brown paper (Table III). Except in the case of 
1 See foot-note on p. 686. 
Z z 
