151 
chance” is used and it is thought that this sticking-chance 
is closely connected with the electric charge. The sticking 
of Paramaecium is promoted for a good deal by a rather 
high .concentration of carbonic acid of the medium, 
Chlamydomonas too can attach itself very well in very 
weak acid solutions. Before the concentration runs so 
high that the motility has diminished a great deal, there 
is found with numerous acids a region of concentrations 
where the inclination to go on sticking is very strong. 
The reaction on the light is very well executed then, 
besides the motility is great enough to react to gravity. 
The fact that no sinking takes place in the meantime is 
caused by the algae get attached when in contact with 
the glass. In those circumstances we get to see a green 
stripe, which does not sink to the bottom. (See fig. 1 À, 
pag. 34). This phenomenon appeared very nice in my 
experiments, when [ worked with solutions of potassium 
salphate, made sour by small quantities of sulphuric acid. 
In solutions of known composition Î never found the 
inclination to stick with a distinct alkaline reaction. 
In the cultures of Chlamydomonas too the inclination 
to stick often appears. For days the culture-fluid can 
possess the composition fit for that. I have been unable 
to make out whether in such a period the culture-fluid was 
also slightly acid. This is caused by the presence of all 
sorts of substances in the culture-fluid, which cause that 
the hydrion concentration of it electrometrically cannot 
be easily defined. How great the sticking-force is may 
appear from the information, that often the attaching we 
can suck away the culture-fluid with a pipette without 
the algae being taken along by the fluid. I will just draw 
the attention that the before-mentioned state of the algae 
only appears with concentrations, which come very 
close to the concentrations, that make the mobility 
stop; we always are then just before the line of 
