Dr. Constantine Hering. See, British Journal of Homeopathy , Vol. XXXIV. What is the Crotalus ? It is the poison of the Rattlesnake , prepared by trituration. What is the characteristic action of Crotalus ? It causes a yellowness of the skin from disintegration of the blood. Tendency to haemorrhages. In what disease is Crotalus often indicated ? In yellow fever, in the stage of black vomit, where there is low delirium, yellow skin, and oozing of blood from every orifice of the body. It produces a perfect picture of this disease.