18 A Manual of Veterinary Physiology. 



body from proteids, sugar, etc. Succinic acid has been 

 found in the urine after the ingestion of certain fruits con- 

 taining malic acid and asparagin ; it has also been found 

 in some of the internal organs. 



Inorganic Constituents. 



The inorganic substances found in the body are water, 

 gases, and salts. Water forms nearly 60 per cent, of the 

 whole body ; it is taken in with the food and drink, and a 

 small quantity may be formed within the system. 



The Gases of the body are oxygen, nitrogen, and hydro- 

 gen. The two former are taken in with the inspired air, 

 while hydrogen is formed in the intestinal canal as the 

 result of cellulose decomposition. 



The largest portion of the inorganic matter consists of 

 the various Salts of sodium, potassium, calcium, magne- 

 sium, and iron, in the form of chlorides, sulphates, phos- 

 phates, and carbonates. We find that the distribution of 

 these salts throughout the tissues is very variable, some, 

 like bone, are excessively rich, whilst others are remarkably 

 poor in them. Certain tissues and fluids have a preponder- 

 ance of some salts to the exclusion of others. 



The amount of the salts existing in the body depends 

 upon the age of the animal, and their nature is modified 

 by the character of the food partaken of; the daily quantity 

 ingested and stored up is largely affected by the rate of 

 growth, young growing animals storing up mineral matter 

 which the adult rejects. 



In the composition of the milk we may obtain an insight 

 into the nature and quantity of the salts required by growing 

 animals. Bunge gives the following ash analysis of mare's 

 and cow's milk : 



