i»7 
Chlamydomonas and other vegetable cells . 
activity was proportional to the number of free hydrogen ions present, 
unless, of course, any one of the acids has a further specific toxic action 
dependent upon the negative ion. (Hunkel and True.) 
It seems probable, in the above instance, that the velocity of the 
reaction due to the mixture of poisons is equal to the sum of the velocities 
of each specific reaction. When a number of chemical reactions are simul- 
taneously taking place in any system, each proceeds independently of the 
others, and the total change is the sum of all the independent reactions. 
Owing to the difficulty in procuring suitable cultures of Chlamydomonas 
I have been unable to make conclusive experiments with other mixtures of 
poisons, but hope to extend the above results next summer. In the mean- 
while these results can only be regarded as preliminary. 
Finally I have to express my thanks to Miss Chick for several valuable 
suggestions, and to Dr. F. F. Blackman for his kind help throughout. 
