In a former publication about the influence of temperature on physiological processes of the yeast1) I showed that in general the studies on this subject had not been carried out in such a manner that important conclusions could be drawn from the results obtained. It was especially demonstrated in the above mentioned study that the present data do not answer to the question whether there is a difference between the influence of a rise of temperature on a physiological and on a physical or chemical process. This view also concerns the influence of temperature on the COo-assimilation, notwithstanding that Blackman2) studied this subject on much better principles than his predecessors.