MEDICINES WHICH ACT UPON THE BLOOD 447 



The nutritive material so constantly being given up by the blood for 

 the sustenance of the body is renewed by the food in its passage along the 

 digestive canal. The blood also serves as a vehicle to remove waste pro- 

 ducts from the body, chiefly by the lungs, kidneys, and skin, and through 

 its medium the body is affected in various ways for good or ill. If from 

 any cause it is deficient in the materials needed for repair or secretion, the 

 body as a whole or some part thereof will suffer, as will also be the case 

 if some deleterious matter be allowed to remain in the blood-stream in 

 excessive quantity, or beyond the time when it should be separated and 

 passed out. 



It is intended by the foregoing remarks to show how the nutrition of 

 the body may be affected by introducing into the blood agents which, 

 being carried to all parts of the system, exercise some influence upon its 

 tissues. 



The preparations of iron in forms not detrimental to digestion, together 

 with suitable diet, appear to increase the production of red corpuscles and 

 improve the general health. 



It is sometimes desirable to employ substances which, instead of in- 

 ducing the red blood corpuscles to give up oxygen freely, will arrest 

 combustion. Where the body-heat has risen above the normal standard, 

 and a condition of fever prevails, we employ for this purpose quinine, 

 alcohol, salicine, and some other agents, the effect of which is to reduce 

 temperature. 



Medicines also act upon the blood by increasing the amount of albumen, 

 salts, fat, phosphorus, &c. 



BLOOD TONICS 



These are remedies which supply materials in which the blood is 

 deficient, and thereby improve its quality; as the greater number of 

 them also increase the red colouring matter of the corpuscles, they are 

 called haematinics. 



Iron. At the head of the list stands iron. The preparations most in 

 use for horses are the sulphate in crystal or exsiccated, then come reduced 

 iron, saccharated carbonate and phosphate, tincture (steel drops), iodide of 

 iron, and arseniate of iron. The citrate and tartrate might sometimes be 

 used for horses with advantage, although much more costly than the first- 

 named preparations, which are most largely employed. 



Action and Use of Iron. Iron in its various forms, but more 

 particularly in certain solutions, has a direct effect upon the .tissues with 

 which it comes in contact and before it enters the circulation. 



