THE AXIAL GRADIENT IN CILIATE INFUSORIA

1. An axial gradient in susceptibility to KCN is present in Stentor, Stylonychia, Vorticella, Carchesium and Paramœcium. This suceptibility gradient indicates the existence of a gradient in rate of metabolism or of oxidation processes.2. In all forms examined the anterior or apical region is the highest point in the general gradient, although localized regions of still higher rate such as the vacuolar regions of Paramœcium may exist.3. A close parallelism exists between the character of the gradient and the morphological and physiological features of the species. Where the gradient is uniform and slight, structural and physiological differences along the axis are slight and where the changes in steepness are great, marked morphological and physiological differences are present.4. The facts indicate that the axial gradient is the dynamic basis of morphological and physiological polarity in the ciliate infusoria as well as in other organisms.