CHAPTER III. 
The systematic investigation of the influence of 
electrolytes on the motility of Chlamydomonas 
variabilis Dangeard. 
$ 1. The judgment on the motility of the organismes, 
In the preceding chapter we have seen that the electrolyt- 
concentration of the watery medium, in which Chlamy- 
domonas is, is of a very great influence on its activity, 
i. e. the power to react to light, gravity, chemotactica 
and contact. 
To learn a little more about this influence of the 
electrolyt-concentration, it seemed desirable to me to 
follow systematically the motility of Chlamydomonas in 
solutions of electrolytes. This has chiefly been the aim of 
my experiments. 
Firstly we tried to find a method to observe the influence 
of the concentration of electrolytes in an easy, if possible 
macroscopic way. The motility of the cilia gradually 
diminishes with the increase of the concentration of the 
solution. To express the grade of motility for every case, 
by a number did not seem easy to me. Meanwhile it was 
very simple to observe two states of motility, namely such 
a motility, that the reactions on the light, to gravity etc., 
could be distinctly observed and a state of immotility or 
a thus diminished motility, that these reactions were no 
longer carried out. We are now looking for the concen- 
