TRANSPLANTABLE TUMORS OF THE FOWL: A NEGLECTED MATERIAL FOR CANCER RESEARCH

The recognition that neoplasms exist in many species of animals throughout the vertebrate world has given to the tumor problem a broader biologic significance. And at first glance it appears strange that so few animal forms have been utilized for experimental cancer research. Attention has centered on the new growths of the rat and mouse, on a peculiar round-celled tumor of the dog, transmissible by coitus, a dubious tumor of wild hares, endemic in certain portions of Germany, and on a thyroid growth of fishes, the exact nature of which is still under dispute. There exist good reasons for this limitation. The animal employed for tumor work must be available in quantity and capable of thriving under laboratory conditions; and its "spontaneous" growths must be transplantable. True tumors are rare in cats, rabbits and guinea-pigs, and, while more frequent in dogs, are difficult to study because of the number of