DIGESTIBILITY OF SOME ANIMAL FATS. 15 
The experimenters themselves were the subjects, and found that 
95.43 per cent of butter fat was digested. 
Luhrig 1 found that butter in a basal ration of meat, bread, and 
vegetables was 96 per cent digested by a healthy man 29 years old. 
In a later paper 2 he reports a digestibility of 97 per cent. 
Another series of experiments in which the experimenters were 
subjects was conducted by Wibbens and Huizenga, 3 who compared 
butter and sana (a butter substitute which contained no milk fat). 
A simple mixed diet was eaten during periods of three days' duration. 
For one subject the fat digestibilities were: Butter, 97.33 per cent; 
sana, 95.3 per cent; for the other subject, butter, 96.5; sana, 73.79 
per cent. 
A much longer experimental period, one of 28 days' duration, 
divided into a fore period of 7 days, a period of 14 days on the special 
diet studied, and an after period of 7 days, was preferred by Von 
Gerlach. 4 He determined the thoroughness of digestion of butter and 
of a commercial product called "sanella" (of vegetable origin), when 
the basal ration consisted of rice, zweiback, and oatmeal. Both fats 
were 97 per cent digested. 
Flurin 5 and Levites 5 have found that butter was 96 per cent 
assimilated. 
Investigating the digestibility of the protein, fat, and carbohydrate 
contents of the ordinary mixed diet, Atwater 6 used varying amounts 
of butter (40 grams to 343 grams per man per day) in the ration, and 
concluded that for three different subjects in 21 experiments the fat 
of the diet was 95.9 per cent available to the body. 
It is difficult to compare the results of all these investigations, since 
the experimental conditions were not of similar nature. In the main, 
however, they show that butter fat is very well assimilated. 
In the eight tests recently conducted in this laboratory conditions 
were more nearly uniform, as the butter was added to the same simple 
mixed diet and eaten by the same subjects who participated in the 
other experiments. The results which were obtained follow. 
1 Ztschr. Untersuch. Nahr. u. Genussmtl., 2 (1899), No. 6, pp. 484-506. 
2 Idem, No. 10, pp. 769-783. 
s Pfliiger's Arch. Physiol., 83 (1901), No. 10-12, pp. 609-618. 
* Ztschr. Phys. u. Diatet: Ther., 12 (1908-9), No. 2, pp. 102-110. 
5 Loc. cit. 
5 Connecticut Storrs Sta. Rpt. 1901, p. 235. 
