184 
Of the proteïns it is known that they can combine with 
various quantities of base or of acid. According to their 
taking up one molecule of acid or an other number, 
various compounds are formed. People do not agree 
about the stability of the thus formed compounds. 
T. B. Robertson thinks to have proved, that they are 
stable with a set H-ion concentration. Besides these com- 
pounds greatly differ in their conduct towards salts. Is 
Robertson's opinion right, then the H-ion concentra- 
tions, where the maximums or minimums in our figures 
are to be found, agree perhaps with the H-ion concen- 
trations, by which the colloïdal substances from the pro- 
toplasm form stable compounds with various quantities of 
acid or base. To make things still clearer, we can say, 
that the phenomena, which we study of Chlamydomonas, 
take place in a region of H-ion concentrations, lying 
between [H] = 10-.and [H]=1077; Ina boots 
Robertson it is stated, that a compound of caseïn at 
neutrality against litmus ([H] — 10-7) contains 1,5 ‘/, CaO, 
while caseïin combines with 2,4°/, CaO at neutrality 
against phenolphthaleïn ([H] — 10). 
Though it is probable, that in both cases, we have to 
do with mixtures of different compounds of caseïn and 
calciumhydroxyde we can state from the data, that in the 
region of the H-ion concentrations, in which Chlamydo- 
monas is movable different compounds of plasmaproteïns 
and base and acid can be expected. 
8 5. The influence of the salts in the motility of 
Chlamydomonas can only be compared with 
its influence on suspensoiïds. 
The representation which we have obtained of the 
conduct of Chlamydomonas under the influence of salts 
