Histological Changes in the Combs and Ear Lobes of Chickens Treated with Methylcholanthrene1

NUMEROUS experiments have been carried out during the past 25 years to determine the susceptibility of a wide variety of animal species to the initiating action of carcinogens. It is well known, now, that over 400 chemical substances are potent carcinogens when applied to the skin of small rodents (Hartwell, 1951). Both cytological and histological changes in the skin of the mouse treated with poly-cyclic hydrocarbons have been ably dis-cussed by Page (1938), Orr (1938)