188 
we have given of the course of the middle part of the 
curves, yet the possibility is great, that in the solutions 
of KNO, and of KCI the plasmcolloïds, respectively by 
0,00010 n. KOH (fig. 5, page 57) and by 0,00025 n. 
KOH (fig. 4, page 56) are isoëlectric. We see namely, 
that the salts in these concentrations of potassium 
hydroxyd have the least influence. In both cases we find 
the isoëlectric point in a weak alkaline solution. The fact 
that the isoëlectric point is not found in the same place 
with the various salts, will be chiefly caused by the fact 
that the ions of the salts have an influence on the electric 
state of the plasmcolloïds. Moreover it is told in chapter III, 
that the results for the solutions of different salts may 
only be compared with reservation. Meanwhile [ think 
that the figures point out that the isoëlectric state is to 
be found with a weak alkaline reaction. 
$ 7. Electric phenomena at the surface of the glass cause 
complications at the reactions of Chlamydomonas. 
There are some phenomena, which might help to find 
the isoëlectric point. Discharged or nearly discharged 
particles stick together, when they touch one another. 
They can also attach themselves to a firm object, that is 
not or but little charged. The cilia of Chlamydomonas 
consist of naked protoplasm. When the plasmcolloïds 
contain a certain charge, the cilia can also show that 
charge. In a solution, in which the plasmcolloïds are 
isoëlectric, we might expect, that the algae with the cilia 
stick to the side. Both phenomena act indeed, under 
special circumstances. We already discussed in chapter II 
the sticking of Chlamydomonas to the glass side. We 
called the phenomenon a thigmotactic reaction. With the 
different salts it did not always appear with the same 
