161 
sible, in the solutions, of which we will examine the influence. 
This transporting of the algae is very easy, when we take 
advantage of the inclination to attaching and the reaction 
to gravity. The inclination to sticking to the side was 
very great in cultures, in which the object was present 
in a suflicient number. 
The tubes were filled with the culture-fluid by means 
of a pipette. Now I let them stand upright for about ten 
minutes, exposed to one-sided diffuse day-light. Under the 
influence of the light the algae moved to one side of the 
glass tube, where they attached thimselves (see 1. A). 
After ten minutes the culture-fluid was sucked away with 
a pipette. The algae remained fixed to the side. As there 
always remained behind something of the culture-fluid to 
the sides of the tube, I washed with a definite quantity 
of distilled water. After this water had been put into the 
tubes the algae were shaked with it. After that the tubes 
were placed vertically again. The inclination to sticking 
had now disappeared, but the reaction to gravity took 
care, that in a short time all algae were closely amassed 
on the bottom of the tube (see 1. B. and C.). By means 
of a pipette the above washing-fluid could be easely taken 
away. The staying for a short time in distilled water was 
of no influence on the sensibility of the algae for the 
solutions. Only when the staying in it lasted longer than 
half an hour, I could perceive, that the algae could bear 
a smaller concentration. After these preparations the tubes 
were filled with the solutions, the influence of it had to 
be controlled. 0,6 cM* of these solutions was brought to 
the organisms. By using more or less of culture-fluid for 
the filling of the tubes, the number of the algae that 
partook of each experiment, could be taken the same to 
the eye. 
Recueil des trav. bot. néerl. Vol. XVII 1920. 11 
