76 AMERICAN FARMER'S HORSE BOOK. 



general necrosis— that is, "death of the bones." During its 

 progress, the bones of the entire system, from a lack of ma- 

 terial in the blood, gradually waste away, so that, after the 

 death of its victims, they are frequently found to be no more 

 than one-half, or even one-fourth, their usual thickness while 

 in a healthy condition. They become mere shells, entirely 

 destitute of marrow, and so brittle as to be easily broken by 

 the pressure of the foot, or by a blow from the blade of a 

 large pocket-knife. Before a fatal termination has been 

 reached, it sometimes occurs that the bones of the fore-legs, 

 unable longer to bear the weight of the body, actually break 

 between the knee and ankle-joint. 



As stated above, the disease first makes its appearance m 

 the head and jaws; its immediate seat is in the marrow of 

 the up{>er and lower jaw-bones, which become carious, or ul- 

 cerated. When fever is present in the animal system, it al- 

 ways has a strong tendency to locate in some member which 

 discharges one of the vital, or at least important, functions, 

 and which is, therefore, much in use. It follows from this 

 that the part in most severe exercise is the one most of all 

 likely to be ajfected, and hence the development of this dis- 

 ease at first in the head and jaws. The constant and severe 

 exercise of grinding the hard, flinty corn irritates and inflames 

 the te'eth and gums, and it is in them and in the jaws that 

 the fever in the system makes haste to establish itself. The 

 marrow of the bones in the head is next attacked, changing 

 to a thick and putrid yellow matter. The swelling of the 

 head and jaws is an ulcerated enlargement of the bones,— 

 simply an effort of nature to discharge this matter, and so 

 to throw off the disease. As an evidence of this, a minute 

 examination will show that the bones are filled with a tissue 

 of little irregular cells, or cavities, and that the entire space 

 occupied by the marrow is becoming of a scaly or spongy 

 growth of bone. It is plain that a general destruction of the 

 bony tissue is rapidly going forward. If its progress is not 

 now arrested, this will spread through the whole body. In 

 several cases examined after death by the author, the bones 



