22 BULLETIN 613, U. S. DEPARTMENT OF AGRICULTURE. 
prove a satisfactory source of energy for the dietary whether eaten 
as a separate fat or as a constituent of ox-tail soup. 
It has often been noted that fats from the different parts of the 
body possess different chemical and physical characteristics. In this 
connection it is interesting to note the values obtained for the di- 
gestibility of the different beef fats reported in this and other bulle- 
tins of this series which were for beef tallow 1 93 per cent, beef- 
brisket fat 2 97.4 per cent, hard-palate fat 93.7 per cent, ox-marrow 
fat 93.5 per cent, and ox-tail fat 96.6 per cent. These values would, 
of course, be more directly comparable had it been possible to secure 
a sufficient supply of these different fats from a single animal. 
TURTLE FAT. 
The flesh of the green turtle (Chelonia my das), a sea turtle which 
lives mostly in deep water and feeds largely upon vegetable matter, 
is used considerably for food. The portion of the flesh known as 
" calif ash " adhering to the upper shell, has a high oil content, is 
of a dull greenish color, and is very highly prized, being used 
in the preparation of turtle soup. According to Ditmar 3 the name 
green turtle is due to the greenish color of the oil. 
The experiments which follow were conducted to secure data con- 
cerning the extent to which green-turtle fat is utilized by the body. 
Through the courtesy of R. L. Coker of the United States Bureau of 
Fisheries, several cans of so-called turtle fat were secured from a 
Florida dealer. On opening, the cans were found to contain a dull 
greenish substance, the " califash," resembling liver in appearance, 
and surrounded by small quantities of a yellow oil which had sepa- 
rated from it. For the sake of uniformity with other experiments, 
the canned turtle fat was rendered and fed in the same way as 
other fats studied. In order to secure as much of the oil as possible, 
the mass was passed through an ordinary household meat cutter and 
was rendered by heating in a double boiler. The resulting oil was 
of a yellow color without any noticeable odor. 
Four three-day digestion tests were made of green-turtle fat and 
the results which were obtained are reported in the tables which 
follow. 
1 U. S. Dept. Agr. Bui. 310 (1915), p. 21. 
2 U. S. Dept. Agr. Bui. 507 (1917), p. 18. 
3 Reptiles of the World. New York : Sturgis and Walton, p. 14. 
