280 DADD'S VETERINARY MEDICINE AND SURGERY. 



p 0S t — one which appears to form an integral part of that ?urse 

 inflicted on the whole creation by the fall of man. 



The importance of cleanliness, and its concomitant health, "o 

 prevent contagion, may be further illustrated. We have just seen 

 above that an acarus, although a loathsome pest, is yet very nice 

 in its taste, and particular about a nidus in which to deposit and 

 hatch its eggs. It enjoys the highest degree of prosperity on the 

 unhealthy skin, multiplying there fastest; Su that if it creeps 

 from it to the opposite — the sleek, healthy one of the horse or ox, 

 or dry wool of the sheep — it feels itself from home, and, before it 

 even reaches the skin, may be bruised or shaken off. If, however, 

 it creeps upon the unhealthy animal with its staring coat, it soon 

 reaches the skin, and commences its direful work, every thing 

 there being congenial to his happiness; hence the incredible 

 speed at which it propagates its species, until it either consumes 

 its victim alive, or is arrested at its fatal work by the timely 

 unguent of the veterinary surgeon. 



Again : when a dirty animal shakes itself, as it invaria jly does 

 after rubbing itself against any thing, less or more suirf, dan- 

 druff, and dust is thrown into the atmosphere, and carried to a 

 distance by high wind. Now, under such circunwances, whca 

 affected with scabies, it is manifest that the smallest of these puny 

 insects, as well as their eggs, will be blown from one pasture tc 

 another ; that the latter will lodge in the dirty staring coat of 

 the unhealthy animal, when they will be blown off that of the 

 clean sleek one, or be brushed off before they reach the skin, or 

 any nidus capable of hatching them. In this manner we can 

 trace contagion from one animal to another, and thus account, in 

 harmony with entomological science, for what has hitherto been 

 termed spontaneous cases of scabies" in some of our domesticated 

 animals, while others have escaped the disease, though all herd- 

 ing together in one field. We can also account for the fact why 

 the disease is more liable to break out among sheep than horses 

 and cattle, without coming in contact with strange flocks, because 

 the coats of the latter are more likely to be impregnated with 

 eggs than those of the former, while they afford a better nidus for 

 hatching them. 



With -egard to health, it has even been said that the blood of 

 scabbed animals is diseased : nav. that the blood of all animals is 

 loaded, more or less with the eggs of acari, and that they are 



