While attempting to produce experimental dietary arteriosclerosis in rats, we observed neoplastic growths in animals that had been on the diet for more than a year and a half. Most of the tumors appeared to be hepatomas, and these are the subject of the present report. These lesions are of particular interest because of the striking difference between our animals, which were obese, and the malnourished individuals that characteristically develop tumors of the liver in the presence of a

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... al deficiency (3, 4). PROCEDURE Ten male and ten female albino rats were placed on a diet designed to produce arteriosclerosis. The diet consisted of 5 per cent powdered egg yolk (Armour's) in whole milk. The mixture was homogenized in a Waring Blendor, but during the course of the day the yolk rose to the top of the crocks, so that the composition of the diet as ingested was more than 5 per cent egg yolk. Fresh diet was distributed morning and evening except on Sundays, when the ~4-hour ration was given in the morning. The animals were purposely chosen from different age groups. The males were 10-~3 weeks old with an average age of 16 weeks. Their weights ranged from 169 to 340 gin., with an average of ~51 gin. The females were 15-19 weeks of age, with an average of 17 weeks. The weight of the females was 170-197 gin., with an average of ]80 gin. The animals were weighed once a month throughout the experiment. Wire-floored cages were used for the 1st year, at which time some of the animals developed sore feet, so they were all transferred to cages with soft wood shavings. When animals appeared to be moribund they were sacrificed. Some died spontaneously, and all surviving animals were sacrificed at the end of a ~-year period. With the animals under light ether * This study was supported in part by a grant-in-aid from the Benjamin Gruskin Fund of the Lakeland Foundation. anesthesia, blood was drawn from the heart until death occurred. Material for histologic studies was fixed in buffered formalin (1:10). The following chemical determinations were made on the blood serum: total cholesterol by the Chancy modification of the Sperry-Schoenheimer method, 1 total serum lipid by a turbidimetric method of Huerga and Popper, 2 phospholipid by the method of Youngsburg and Youngsburg (7) , and nonprotein nitrogen (NPN) by a slight modification of the Folin-Wu technic (~), 10 per cent trichloroacetic acid being used for deproteinization. Total liver fat was determined by chloroform extraction of the dried tissue in the Soxhlet apparatus followed by a second extraction with petroleum ether. RESULTS Incidence of "hepatomas."--Tumors which appeared to be hepatomas developed in three out of four males which survived on the diet for over 1.5 years. Four other males which survived on the diet for more than I year but less than 1.5 years did not have hepatic tumors. The other two which survived less than 1 year did not have a tumor. Nine of the ten females survived on the diet for over a year, and six for more than a year and a half. Of these six, three developed hepatic tumors. That is, six of the ten animals surviving for over 1.5 years had hepatic tumors. The average age of the tumor-bearing males was 111 weeks (range, 98-119); the average of the females was also 111 weeks (range, 10~-119). Animals exceeding the age of 98 weeks without developing the hepatic tumors were one male, age 101 weeks, and four females having an average age of 116 weeks (range, I04-1~3). One of these females, age 116 weeks, had been removed from the regimen after 70 weeks so should not be considered in this group. Of the ten animals reaching an age of 98 weeks or more and ingesting the milk-egg 1 I. C. Chaney, personal communication. 2 j. de la Huerga, and H. Popper, personal communication. 441 Research. on July 10, 2020.