32 ; PRINCIPLES OF ANIMAL NUTRITION. 
hand, experiments with cows failed to show any passage of linseed 
oil as such into the milk. 
Leube * made subcutaneous injections of melted butter on two 
dogs and found an abundant deposit of butter fat especially under 
the skin of the abdomen, the Reichert-Meiss] number of the fat 
being 20.46 in the first case and 15.3 in the second. Rosenfelt + 
fed fasted dogs with mutton fat and observed a large deposit 
of this fat in all parts of the body. : 
INFLUENCE OF FEEDING ON ComPposiITION OF Fat.—In addition 
to the more purely physiological experiments just cited, there are 
on record a not inconsiderable number of feeding experiments, 
especially upon swine, in which the feeding appears to have 
sensibly influenced the appearance, firmness, melting-point, or 
composition of the body fat. — 
While it is not impossible, however, that in some cases the 
peculiar fats of the food (e.g., the fat of maize or of the oil-meals) 
may have been deposited in the adipose tissue unchanged, it must 
be borne in mind that these experiments were made on mixed rations 
and that undoubtedly there was a considerable production of fat in 
the body from other ingredients of the food. This being the case, 
we are left in doubt as to whether the effect observed is due directly 
to the fat of the food or is to be explained as an effect of the food as 
a whole, or of some unknown ingredients of it, in modifying the 
nature of the metabolism in the fat cells. That such an explana-. 
tion is at least possible would seem to be indicated by the well- 
established fact that marked changes of food do modify the 
metabolism in the milk gland sufficiently to materially affect the 
proportion of volatile fatty acids in butter fat. 
A striking example of the possibility of such an effect upon the 
metabolism of the fat cells is afforded by the recent investigations of 
Shutt { into the causes of “soft” pork. On the average of a con- 
siderable number of animals, he finds that the shoulder and loin fat 
of pigs fed exclusively on maize shows a very low melting-point 
and a high iodine absorption number, indicating a large percentage 
of olein, and inclines to attribute this effect to the oil of the maize. 
When, however, he fed skim milk with the maize, he obtained pork 
* Thier. Chem. Ber., 25, 45. + Ibid., 25, 44, 
¢ Canada: Dominion Experiment Station, Bull. 38. 
