158 
but besides this, it is desirable to work with glass vessels, 
which have always the same diameter. With experiments, 
that took place six-fold, it struck me that a difference 
in diametre of the tubes gave rise to deviating results. 
[I worked with narrow glass tubes, tapering at the bottom 
and shutted there by melting. (See fig. 1, pag. 34), By 
observing that the various tubes were filled alike, when 
they contained the same quantity of fluid, I had a guarantee, 
that the diametre had the required size. 
It is not probable that the temperature has a great 
influence on this phenomenon we are studying. 
When still engaged with preliminary experiments on 
the various reactions of Chlamydomonas, T1 controlled 
the influence of the temperature. By means of tapwater, 
saturated with carbonic acid, Î obtained by a mixing 
up with boiled out tapwater solutions, which changed 
regularly, as far as the concentration of carbonic acid, 
was concerned. In the way, which was also applied later 
on Î examined the motility of the Alga to the reaction 
to gravity and so it was possible to state the limiting 
concentrations for the carbonic acid solutions. The experi- 
ments were done by 25° C. and by about 0° C., to obtain 
the latter temperature, the tubes, in which the reaction 
was to take place, were steeped in ice-water. For the 
low temperature the same limiting concentrations were 
found as for 25 GC; 
It was observed that with the low temperature the 
algae do not attach themselves in the same solutions in 
which they did it very fine by 25° C. I am of opinion 
that my preliminary experiment proves sufliciently, that 
the influence of the temperature on the motility of 
Chlamydomonas in solutions of electrolytes is not great. 
This opinion is the same as Voegler's (1891) or the 
influence of the temperature on the value for the threshold 
of chemitactica for spermatozoa of Dicksonia antarctica. 
