98 VETEEINAEY HYGIENE 



33-5 parts of urea, 51-4 parts of fat, and 27-4 parts of 

 carbonic acid. 



3. From the carbo-hydrates in the food. 



DeaUng first of all with the fat in the food, this in the diet 

 of herbivora is very small, the crude fat in vegetable tissues 

 exists only in trifling amount, and is more of the nature of 

 wax, which is indigestible. In cereals such as oats and 

 maize, a fairly pure fat may be obtained. 



The fat in the food to be of any use must be allied to the 

 animal fats, foreign fats are either not absorbed, or are 

 rapidly oxidised. The fat found in vegetable tissue (ex- 

 cluding the wax), is very similar to the body fat, and is 

 therefore capable of being utilized. 



Fat produced from proteid is more easily oxidised in the 

 body than the fat originally existing in the food, and the 

 fat from the food is more easily utilized than the fat 

 actually deposited in the tissues. 



The formation of fat from carbo-hydrate is beyond all 

 doubt, but before conversion into fat it must first be 

 changed into sugar. Sugar is more easily oxidised than 

 fat, and thus starch exercises a protective influence over 

 the body fat, and at the same time, as previously pointed 

 out, economises the consumption of proteid. 



Carbo-hydrates. 



This constitutes a large and important group in the 

 vegetable kingdom, and is represented by starch and its 

 derivatives, the various forms of sugar, and cellulose. 



Starch is a highly complex substance contained within 

 the grain of plants. The starch granules vary in shape 

 depending upon their source, those of potato, beans, wheat, 

 etc., are microscopically quite distinctive. 



In grains and roots the amount of carbo-hydrate in the 

 form of starch or sugar is very evident, but with grass, hay, 

 and fodders generally, these are largely replaced by gummy 

 material, very little starch or sugar existing. 



In the digestive system all starch and other allied bodies 



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