Abstract
1. A sarcoma of the mouse which has proved to be transplantable to a great variety of strains of mice does not furnish an exception to the theory that transplantability is controlled by genetic factors, since this tumor possesses some characteristics that are more than probably genetic. 2. The phenomenon of the assumption of tissue specificity on the part of the host may possibly be of genetic origin. 3. The evidence suggests that the gonads have some influence on the assumption of tissue specificity on the part of the host. 4. The growth rate of the transplanted tumor may possibly be correlated with the genetic constitution of the host.