94 



1916 ANNUAL REPORT 







bUBJEOl 



T 

 1. 







1-2 



Butter 



298.7 



20.0 



278.7 



93.30 



Q A 



Butter 



325.4 



o-i o 



orvo f* 



dOo.o 



93.30 



o-o 



Avocado 



292.6 



16.8 



275.8 



94.25 



7-y 



Avocado 



521.9 



32.7 



489.2 



93.77 



10-11 



Butter 



325.4 



16.7 



308.7 



94.89 



12-15 



Avocado 



610.7 



42.2 



568.5 



93.09 



16-17 



Butter 



314.5 



19.9 



294.6 



93.65 





Average digestibility of fat on 



butter diet . . 





93.80 





Average digestibility of fat on 



avocado diet 





,93.70 







SUBJECT II. 







1-2 



Butter 



313.4 



22.8 



290.6 



92.73 



3-4 



Avocado 



280.6 



30.5 



250.1 



89.13 



*equals 3-4. 



The coefficients uf digestibility have been calculated in the usual 

 way on the assumption that the fat of the feces represents unabsorbed 

 food fat. This assumption can not be held as valid for several reasons: 



(1) The feces of a fasting animal contain fat. 



(2) On a diet free from cellulose the amounts of fat in the food 

 may vary considerably v^ithout a proportionate variation in 

 the feces fat. 



(3) In the present experiment the feces fat during the avocado 

 periods was not of the consistency of avocado oil but differed 

 not at all in general • appearance from the feces fat of the 

 butter periods. (This point is still under investigation). 



But, even though the fat of the feces is not unabsorbea food fat, 

 it may nevertheless be said that its amount is influenced by the quality 

 and quantity of the diet, and that the difference between feces fat and 

 food fat represents the net intake of fat by the organism on the given 

 diet. 



From the table the percentage utilization, or digestibility of the 

 fat on the butter and avocado diets may be seen: in Subject I an 

 average of 93.80 per cent for butter fat as against 93.70 per cent for 

 the avocado; in Subject II 92.73 per cent and 89.13 per cent respectively. 

 In a paper published recently (Bull. 310, U. S. Dept. of Agriculture, Nov. 

 1915) Langworthy and Holmes show that the digestibility of butter fat 

 in their subjects varied from 90.9 per cent to 96.3 per cent with an 

 average of 93.9 per cent, and since the value obtained on the present 

 subject is 93.8 per cent it may rightfully be concluded that the fat 

 digestion of this individual at the time was very near the average and 

 that the digestibility of avocado fat is on a par with that of butter 

 fat. 



The single 4-day experiment on Subject II is of less value than the 

 several and continued tests made on Subject I, but from the data of 

 Subject II it would be concluded that the digestibility of avocado fat 

 was not below that of beef fat, a value of 89 per cent being found by 

 Langworthy and Holmes for this fat. 



The above mentioned mvestigators find that of the fats tested 

 (butter, lard, beef fat and mutton fat) those of low melting points are 



