ON THE GEOTROPIC ORIENTATION OF YOUNG MAMMALS.

Constants in equations of curves describing the geotropic orientation of young rats are repeatedly obtainable from litters of successive generations of the same inbred strains. Different inbred strains have been obtained for which the respective constants are quite unlike. Such findings show how necessary it is to employ biologically uniform material in experiments of this kind. And at the same time they are convenient as a starting point for genetic analysis.