Problems of growth have interested numberless workers, especially during the past ten years. The growth of young animals as well as the growth of tumor cells has been investigated with great care, and attention has been directed to various food factors. We believe that most workers assume that the most rapid growth is to be found in malignant tumor development, which at times may exceed the speed of growth of the embryo or fetus. We have been impressed with the great speed of repair of the normal liver following a type necrosis due to chloroform. Under such circumstances the formation of cell protoplasm proceeds with remarkable rapidity and exceeds any growth speed with which we are familiar. To illustrate in familiar figures — a healthy adult human of 75 kilograms, or 165 pounds, body weight, will possess a liver weighing approximately 1,700 gm. A suitable chloroform anesthesia during a fasting