THE GEEAT SAFETY VALVE. 297 



not unknown, but disappears easily with lower fare, and bowels 

 relaxed with succulent food. 



DISEASES OF THE SKIN. 



734. — The skin of the horse, like our own skin, is a wonder- 

 fully fine sieve, through which water is constantly passinj? and 

 taking away worn out materials, injurious acids or gases, and 

 even mineral or vegetable poisons, that have been poured into the 

 stomach. It is the great safety valve of the system, more 

 constantly essential to life than any other, except the lungs. 

 An animal with completely obstructed skin, dies far more 

 quickly than with obstructed bowels or kidneys. The great 

 capacity of the skiu to regulate the temperature of the body is 

 altogether beyond human comprehension. It is, too, the only 

 one of the depurgatory surfaces that we can really get at, and 

 that submits kindly to our interferences. The internal skin is a 

 continuation of the mucous membrane, or of the skin that covers 

 all the internal cavities. In the nose the two skins are less alike 

 either in appearance or function, than in the human body, but 

 there is the same constant sympathy between the inside and 

 outside membrane, so that it is impossible to benefit or injure 

 the one without the eflFect being felt on the other. This is a 

 fact known to all physiologists and recognized by medical 

 practioners of every school. 



735. — Until within the last fifty years the skin of the horse 

 was much better understood and much better treated than our 

 own. The great assistance it could be made to give, both to the 

 digestive organs and to the lungs, was early discovered by trainers 

 for tlie racecourse or the hunting field, and horses in such hands 

 are not only found with skins invariably healthy, but almost 

 always kept in a very high state of efficiency by the frequent and 

 vigorous use of the brush. In fact it is not common to find any 

 disease of the skin in any well managed stable. 



SURFEIT. 



73G. — Is a name used to describe any disease of the skin for 

 which no other name can be found. It may be the result of 



