regards the various salts required for the building up of the 

 animal tissues. Sodium chloride, for instance, is absolutely 

 necessary for the preservation of health. It is needed for 

 the formation of blood, of gastric juice and of bile, and for 

 the digestion of albumen. The salt taste of perspiration and 

 tears is a proof of its presence in the blood. A salt lick 

 should be provided in every cow-house and stable. But excess 

 of common salt is very injurious to the animal system, 

 producing various skin diseases. Dogs fed on highly salted 

 food are particularly subject to eczema; and scurvy in man 

 is due to the same cause. 



1.044, Similarly, a certain amount of potash is needed by 

 the animal, and the favourite food of farm-animals, viz. y grass 

 and other green herbs, is rich in potash. Deficiency of 

 potash means impaired tissue nutrition; but excess also is 

 highly injurious ; as it induces an excessive fluidity of the 

 blood and consequent increased activity of the kidneys. If 

 food too rich in potash is persisted in, serum may flow from 

 capillaries into the surrounding cavities and tissues, resulting 

 in dropsy. The extra work thrown on the kidney results in 

 their ultimate derangement and disease. Blood also gets 

 poorer in albuminoid matters, i.e. t in fibrinogen and fibrino- 

 plastin, and as a consequence skin eruptions follow. Chlorate 

 of potash so changes the colouring matter of the blood, as 

 to render it useless as a vehicle of oxygen. 



1.045. Phosphates are absolutely necessary for the form- 

 ation of bones and teeth, and if they are not supplied with 

 food in sufficient quantities bone-softening or rickets follow, 

 and a tendency to fracture of bones. The teeth also develope 

 slowly and they tend to decay. Decayed teeth are very 

 common among animals reared on poor pastures. Nerve and 

 brain substances also require a supply of phosphorus for their 

 proper nutriment. On the other hand, an excess of phospha- 

 tic diet results in the breaking up of blood corpuscles, in fatty 

 degeneration of the walls of blood-vessels and of the liver. 



