DESTINATION OF OLEOIDS. 903 



fat, or they may protect and thus spare the fat already in the body. 

 Sugar and starch given with meat or albuminoid food, produce obesity ; 

 they are even more fattening than fat itself, as they are more easily 

 oxidized, and act more effectually as protectors to the other constitu- 

 ents of the body. Ultimately, their elements are, in any case, sub- 

 jected to the same oxidizing processes, yielding carbonic acid and 

 water. Their upward transformation is probably exceptional, because 

 they are more easily oxidizable than fat. 



The fatty matters, or hydro carbons, are usually decomposed into 

 their fatty acids and glycerin, before they enter the chyle, and are 

 probably recomposed there, or in the blood ; possibly, also, they are 

 again decomposed, under the influence of the alkaline constituents of 

 the blood, on the eve of being oxidized. This oxidation may be direct 

 or immediate, into carbonic acid and water ; but the fat may be first 

 employed, perhaps in the formation of the choleic acid of the bile, or 

 of the volatile fatty acids of the milk, butyric, capric, and caproic ; or 

 it may be still further resolved into propionic, formic, or acetic acids, 

 and so pass to the ultimate condition of carbonic acid and water. The 

 hydrogen of fat, being in excess of its oxygen, and not in the propor- 

 tions to form water, as in the carbhydrates, this element and the car- 

 bon, which also exists in excess, demand, for their reduction, a much 

 larger relative supply of oxygen from the air. Hence, in regard to 

 vito-chemical calculations, the fats may be represented by a starch 

 equivalent^ 1 part of fat being equal to 2.4 parts of starch. A minute 

 portion of fat may remain almost unoxidized, in the form of choles- 

 terin. Fat, like the carbhydrates, also saves the metamorphosis of 

 the albuminoid tissues and food ; for if an animal be fed on insufficient 

 animal diet, to which some fat is added, there is less waste, and a 

 smaller consumption, of nitrogenous matter, than if it be fed on a 

 scanty meat diet without fat. A normal proportion of fat in the food 

 also saves the consumption of meat ; for the weight of an animal is 

 then maintained with one-third or one-fourth less meat, than when it 

 is fed on meat alone. An excess of fat in the diet, however, has, as 

 its chief result, an increase of weight, by accumulation of adipose tis- 

 sue. The most successful plan of fattening animals, is not to with- 

 draw the albuminoid foods, but to allow these to remain the same in 

 quantity, and to increase the hydrocarbons and carbhydrates. The 

 researches of Lawes and Gilbert show that in the fattening of ani- 

 mals, much more fat is produced than there is fat in the food, only 

 Jth, or Jd being contained in the food, and therefore, from fds to |ths 

 being produced from other sources, largely from the carbhydrates, but 

 also from any excess of nitrogenous food, after the albuminoid tissues 

 are supplied. This is especially the case, if the non-nitrogenous food 

 be defective, or if an animal be fed on flesh only. (Voit.) 



Alcohol, which may be considered as one type of hydrocarbonaceous 

 food, has been said, by some, to escape wholly unchanged, by the 

 breath and the excretions ; but it is generally believed to be, at least, 

 partly oxidized, either with or without previous conversion into alde- 

 hyde, acetic acid, or some other intermediate substance or substances. 

 It is not supposed to contribute directly to the formation of tissue, 



