177 
susceptibility to the acid is diminished. After that the 
curve goes back, to make another bend soon afterwards 
(till 0,00015 n. H,SO,, 0,06 m. K,SO,), which we may 
think to have arisen from the opposition, which the salt 
gets from the acid. 
- The curve for K;,SO, is not the only argument for the 
different conduct of acid and salt and of base and salt 
mutually on the motility of Chlamydomonas. The course 
of the line for sodium acetate (fig. 3) in the most acid 
- aù — | | n 
| 
S- h$ 
ES 
Œ 
2 
8s- 
v9- 9 L 
=  H9- 
el 
M1 
| 
DH 
Es 
YL- L- 
2U09 uau0l 
01 
| 
) 1 2 3 4 5 6 T 
conc. Na-acetaat 0,011. 
Fig3: 
do 
) 79. 
hL- 
solutions (between [H] = 10°? and [H] = 10°) agrees 
entirely with the opinion, that the influence of acid and 
salt is not additive. 
Though the point, where the curve in the acid solutions 
reaches the ordinate axis, was not fixed, yet we can 
observe, that the line in the denoted region, just as the 
line for K,SO,, makes two bends. If we follow the curve 
from the ordinate axis; then the first bend illustrates the 
Recueil des trav. bot. néerl. Vol. XVII, 1920, 12 
