102 HEALTH AND DISEASE 



or less serious indigestion, ending in recovery under appropriate treat- 

 ment. But the habitual consumption of excessive quantities of food, by 

 horses which are thrown out of work without having the quantity of 

 diet materially reduced, will result in the deposit of large quantities of 

 fat in and upon various organs of the body, some of it on the surface 

 of the heart, in the cellular structure of the liver, and in other organs. 

 In the first instance fatty material may be merely laid up as a deposit 

 in the texture of an organ, or the cells and fibres composing it may 

 undergo complete degeneration, by which its natural structure is con- 

 verted into particles of fat. 



Insufficient food, on the other hand, produces extreme debility, 

 and predisposes an animal to many diseases. 



If the deficiency is chiefly in regard to nitrogenous materials, the 

 muscular structures suffer most, and fatal results may follow. This is 

 especially the case when a horse is compelled, notwithstanding the in- 

 sufficiency of food, to continue its ordinary work. 



Quality Of food has also a considerable influence on nutrition, and 

 foods grown on certain soils are known to be extremely poor in this 

 respect. Where food of inferior quality is supplied on the assumption 

 that it is of good quality, the nutrition of the body will fail to be sus- 

 tained, and wasting results. On certain soils the herbage produced, and 

 even the hay made from it, exercise an injurious influence on the animals 

 which partake of it; at the same time it may not be possible to decide 

 what changes have occurred to render the food deleterious. The scour- 

 ing lands of central Somerset are a case in point, and although investi- 

 gations have been made repeatedly, including analyses of the soil, herbage, 

 and water, the cause of the disease which attacks animals feeding on the 

 pastures has never yet been accurately determined. 



There are many cases in which there is no doubt at all of the fact 

 that weakness results from a diseased condition of the food. It is gener- 

 ally understood that plants suffer from a large number of diseases, many 

 of them being easily recognized, but there is every reason to believe 

 that there are others the exact nature of which has not been determined. 



Among the diseases which are known, those depending upon animal 

 or vegetable parasites are most marked in their character. Plants are 

 attacked by numerous fungi or moulds, which are not only injurious 

 to the plant, but in many cases to the animals which partake of them. 

 Mouldy hay, for example, produces derangement of the digestive organs. 

 Ergotized grain, taken in large quantities, has an extraordinary action 

 upon the animals which consume it, including nervous derangement, 

 associated with mortification of the lower extremities, and occasionally 



