Nature of the Causative Agent of the Rous Fowl Sarcoma

THE opinions of workers in the field of Rous sarcoma are divided into two schools, one of which uses as a working hypothesis the suggestion of Fraenkel1 that the agent is a pure chemical substance or a virus-enzyme, while the other considers it to be a particle resembling a virus. These opinions are represented by two quotations from recent publications. Murphy2 states that ” Without proof that normal tissues harbour the cancer virus, a fantastic conception and one difficult of experimental test, the virus theory for the etiology of cancer appears untenable. The only proved relationship is that a virus may act as a carcinogenic agent in initiating changes leading to malignancy, but has no part in the formal genesis of neoplasms.” Against this may be set the contention of Amies3 that ” The total evidence seems, therefore, sufficiently strong to justify the conclusion that the tumour agents exist in the form of elementary bodies similar to but somewhat smaller than those which represent the causal agents of such typical virus diseases as Vaccinia and Fowl-Pox”.