191 
served, that in most alkaline solutions it did not occur. 
The formation of agregates because the algae with their 
cilia stick together, and the fastening to the side are 
phenomena, which are undoubtedly connected with the 
electric state of the plasmcolloïds. 
However these phenomena have not provided us with 
a means, to control the place of the isoëlectric point. 
Therefore, in the judging of other phenomena in connection 
s 7 
eo 
[e] 
=1 re 
eo os 
IE 
ss SD 
æ x x x 
F Lea * Es | 
eo x x 
3 S < x 
e 
GS: 
TE 
e 
ë 
8 
[æ] LA 
e 
[=2 
L=2 ni L- 
oc L=2 
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0 1 2 2) Li 5 6 Li 8 9 10 11 12 
conc. KN 0, o01n 
Fiqee7e 
with the electric state of the plasmcolloids, we must be 
very careful. Of the other phenomena we have observed, 
two are of great importance, in connection with what 
precedes. Firstly we observed in chapter I, $ 2, that there 
exists an acid-optimum for the chemotactic reaction of 
Chamydomonas. This must lie in the proximity of [H] — 10. 
Moreover we observed (chapter II, $ 5 and 6), that in 
solutions where sticking to the glass takes place positive 
phototaxis can appear, whilst in all other solutions, in 
which the motility is great enough, negative phototaxis 
is observed. 
