The influence of temperature on the geotropic presentation-time

The influence of temperature on physiological processes has often been the subject of investigation. As early even as the beginning of the nineteenth century determinations were made of the maximum, optimum and minimum temperatures of growth. It is especially since the researches of Sachs in 1860 that more and more importance has been attached to these cardinal points of temperature; and the curve representing the connection between a given temperature and a physiological process (generally called the optimum-curve) was thought fully to represent this connection. In the second half of the nineteenth century a good many investigators have tried in various cases to determine this temperature curve, as it was thought the end would be attained in a- given case, by the determination of the cardinal points of temperature. This view has recently changed.