The American Journal of Cancer

Most of the major problems of medicine that can be solved by the study of human material alone have been settled as far as available methods and materials permit. Most of our remaining problems apparently will have to be settled by work with animals, which furnish the essential possibility of control of observations and results, a feature difficult, often impossible, when human material must be used for our investigation. This is particularly true of cancer, whether we are seeking light on the cause or the treatment. Cancer is a disease of such protracted development and course, so variable in its manifestations and duration, often so difficult of diagnosis and differentiation, that satisfactory study of many fundamental problems on the basis of clinical observation is almost or quite impossible. A new impetus to cancer research was received when, through the study of cancer in animals, the investigative work was put upon an experimental basis. Cancer research had come almost to a point of complete despair at the end of the 19th century. Pathologic anatomy had established the relation of cancer tissue to