159 
Between 14° C. and 28° C. the threshold-value remained 
unchanged. 
Since the results of my further experiments denote a 
clear agreement between the phenomena which I studied 
of Chlamydomonas and the flocculation and solution of 
colloïds, it is of importance to point to the fact, that for 
instance the influence of the temperature on the stability of 
suspensoïds is of little importance (Freundlich, page 
368). The temperature, in which my experiments were 
done, changed between 14° C.—28° C. The temperature 
was always noted down. For all experiments with the 
same salt the temperature varied much less. Ît was for 
mysstatements with KNO::20.5° C=247C." In: the 
beginning it seemed better to do the experiments in the 
dark. Possible changes under the influence of a changed 
strength of light would then be excluded. Very soon it 
was proved, however that is was not desirable, to expe- 
riment in the dark. So it struck me directly, that the conduct 
of the Alga in distilled water in the dark, was very uncertain. 
Sometimes in this milieu the sinking took place in a 
splendid way; in other cases it might happen however, 
that the reaction to gravity, under those circumstances, 
did not appear at all in distilled water. 
Meanwhile we must not forget, that we must always 
expect a change of the concentration of carbonic acid 
during the experiment. In diffuse daylight we find as well 
assimilation of carbonic acid as respiration, by which the 
concentration can diminish, increase or remain unchanged. 
In the dark an increase of the concentration of carbonic 
acid can only take place under the influence of the 
respiration. Now it can be derived from the graphic 
representations which shall be given later on, that the con- 
duct in distilled water by the addition of small quantities 
of acid is changed considerably. 
However the ‘increase of the concentration of carbonic 
