PLANTS CONSUMED BY HORSES. 5 



age may be regarded as the gradual calcification of the 

 organism, which in extreme senility renders the performance 

 of the vital functions impossible. Although salts of potash 

 and those of soda (chiefly in common salt) constitute only 

 about aVo^t-h of the entire weight of the animal, they play an 

 indispensable and active part in nutrition ; and as they 

 become rapidly excreted, a continued supply of them is 

 necessary for health. Chlorine, besides being a component of 

 common salt, is also one of hydrochloric acid (HC1), which is 

 found in gastric juice. Silica appears in minute traces in the 

 body ; its chief office being to give hardness to the tissues in 

 which it is present. Although iron does not add more than 

 one ounce to the entire weight of the horse, its presence in the 

 colouring matter of the blood is essential to life ; and its due 

 supply, to health. 



The principal carbo-hydrates, which are found only to a 

 small extent in the body, are animal starch (glycogen), 

 dextrose (grape sugar), and milk sugar. We find traces of 

 grape sugar in the blood, and considerable quantities of 

 glycogen in the cells of thj liver, from which it is removed by 

 the blood in the form of grape sugar. The grape sugar 

 preserves its identity in the circulation for only a short 

 period. 



Phosphoric acid and lactic acid, in small quantities, are the 

 chief acids which are distributed throughout the tissues and 

 fluids of the body. Hydrochloric acid, as just stated, is 

 found in the gastric juice. 



There are other organic compounds which are met with in 

 the system ; but their quantity is so insignificant, that they 

 need not be mentioned. 



COMPOSITION OF PLANTS CONSUMED BY HORSES. 



Plants contain all the chemical elements found in animals, 

 and in nearly similar combinations. 



