HEREDITARY polyposis of the colon is not a congenital disease but a mendelian dominant which is transmitted by father or mother and may be inherited by children of either sex. The polypi are not present at birth but usually appear between puberty and the age of 30. The valuable work by Harrison Cripps,1Cuthbera Dukes2and later Lockhart-Mummery and Dukes3has definitely established the hereditary predisposition and has suggested that its cause is a genetic defect resulting in excessively rapid growth of the intestinal epithelium which is characterized at first by hyperplasia and later by the formation of adenomas and finally progresses, in a large proportion of cases, to carcinoma. The symptoms of this disease are usually diarrhea, the passage of mucus and blood, pain in the lower abdominal area and tenesmus. The condition is usually diagnosed as colitis, and the true nature of the disease is