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distinctness. With KCI a vague thigmotactic reaction was 
observed in some solutions. In the acetate solutions the 
phenomenon was not at all seen. For K,SO, and KNO,; 
it is denoted, in the figures 6, page 66 and 7, page 68, 
by means of the sign X, by which concentrations the 
phenomenon could clearly be seen. 
From the figures can be seen, that the solutions asked 
for were for the greater part weakly acid. At any rate 
the solutions are always more acid than the solutions in 
which we held the plasmcolloïds to be, isoëlectrical. This 
difference can however be explained. If we put water in 
a glass vessel, the glass gets a charge. Freundlich 
thinks, that the charge is caused by the fact that the 
glass absorbs ions. Electrolytes, which are dissolved in 
the water, have an influence on the charge of the glass. 
In alkaline, neutral and extremely weak acid solutions, 
that contain no salt the charge of the glass. as regards 
the water, is a negative one. In the other acid solutions 
the charge strongly decreases. 
We have now probably the following case: the cilia 
are isoëlectric, so discharged in weak alkaline solution; 
the glass has a slight charge in acid solution. It is not 
strange that the phenomenon takes place in weakly acid 
solution. 
For K,SO, (fig. 6) where we also observe the pheno- 
menon in solutions that contain little salt, we see that 
these solutions contain 0,00020—0,00045 n. H,SO.. 
For a comparison we can mention the conduct of the 
catgumparticles from the suspensions of Perrin (conf.: les 
Atomes, page 139). 
These suspensions behave as solutions of negative sus- 
pensoïds. They are discharged in acid solutions, stronger 
than O,01 normal. Here the particles stick together. 
However they attach themselves to the glass already in 
less acid solutions. In these solutions the charge of the 
