Determining the Incidence of Carcinoma. 141 



cholesterol in animal tissues being derived from their diet. This 

 fact suggested the possibility that the incidence of carcinoma in 

 inoculated animals might be diminished by feeding them for a 

 considerable period prior to the inoculation upon a diet poor in 

 cholesterol. 



Accordingly twenty-two white rats, about two months old, 

 were divided without exercising any selection into two lots. One 

 lot of 15 were fed upon a diet composed exclusively of milk; the 

 remainder were fed upon a mixed diet of oats and meat. 



The content of cholesterol in milk, while by no means negligible, 

 is extremely small in comparision with the content of cholesterol 

 in other foodstuffs. Thus Tolmatscheff finds that human milk 

 contains from 0.025 per cent, to 0.039 P er cent, of cholesterol, 1 

 while Bomer and Kirsten find that the fats in cow's milk contain 

 0.5 per cent, cholesterol, corresponding to a content of less than 

 0.02 per cent, in the whole milk. 2 Meat, on the other hand, con- 

 tains from 0.07 to 0.08 per cent, of cholesterol, 3 while the content 

 of phytosterols in seeds is considerable. 4 



Both lots of animals thrived well, the milk-fed animals present- 

 ing an especially well-nourished appearance. 



At the end of two months both lots of rats were inoculated in 

 the axillary region with portions of a Flexner-Jobling carcinoma. 

 The diet of each lot of rats was maintained unaltered. At the 

 end of twenty days the proportion of successful inoculations in 

 each batch of animals was determined, with the following results: 



Milk diet: 10 out of 15 = 67 per cent. 

 Mixed diet: 7 out of 7 = 100 per cent. 



Another batch of half-grown animals obtained at the same time 

 from the same dealer, which were fed upon a mixed diet and 

 inoculated with Flexner-Jobling carcinoma yielded the following 

 results : 



Mixed diet: 55 out of 64 = 86 per cent. 



While the milk-fed animals yielded the lowest percentage of 

 successful inoculations it is evident that the difference between 



1 Tolmatscheff, Hoppe-Seyler's Med.-Chem. Unters., 2 (1867), p. 272. 



2 R. W. Raudnitz, Ergeb. d. Physiol., 2, I (1903), p. 264. 



3 C. Dormeyer, Arch. f. d. ges. Physiol., 65 (1896), p. 99; G. W. Ellis and J. A. 

 Gardner, Proc. Roy. Soc. London, 81 B (1909), p. 507. 



4 F. Czapek, "Biochemie der Pflanzen," Jena, 1905, Vol. I. 



