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acid cannot alone be responsible for the uncertain conduct 
of the Alga in the dark. In the first place the experiment 
takes but little time (ten minutes) Moreover this can be 
seen from the following example: For solutions which 
contain besides 0,00010 n. KOH also KNO:;, one day the 
limiting concentrations of the KNO, were stated for objects 
from a definite culture. The limiting concentrations were 
0,08 n. KNO,; and 0,09 n. KNO.. 
The next day the same limiting concentrations were 
stated with algae from the same culture for solutions, 
which contain besides 0,00010 n. KOH, KNO:. 
It appeared now, that even in 0,005 n. KNO;, could 
not be observed a reaction to gravity. Other experiments 
too from the series of the preceding day were then 
repeated and the conduct of the Alga was entirely changed. 
After the drawbacks of working in the dark had thus 
distinctly come to light, | examined whether in the light 
were obtained less irregular results. This proved indeed 
to be the case. As far as I worked with algae from the 
same culture Ï have, with my experiments in the light, 
never observed anything of similar sudden changes. 
The tubes were thus placed, that they were exposed to 
one-sided diffuse day-light. Naturally the strength of the 
light was rather different. 
& 3. In which manner the algae were brought into the 
solutions of electrolytes. 
We have now found a suitable method to judge of 
the motility. Betore, however, we can go further and can 
examine the influence of various solutions, a means must 
be sought, with which we can transport the algae, free 
from bymixtures and together with as little fluid as pos- 
