Abstract
The inhibiting action of pancreatic tissue was found to be associated with the unsaturated fatty acid fraction. As small an amount of fatty acid as 0.1 mg. inhibited the chicken sarcoma agent contained in 0.2 cc. of a 1:60 aqueous extract of Chicken Tumor I. The unsaturated fatty acid had an acid number and an iodine number similar to those for oleic acid. Commercial oleic acid also was found to inhibit the growth of the chicken sarcoma in comparable quantities.