232 BOx^RD OF AGRICULTURE. [Pub. Doc. 



In whatever way the bacilli are brought to any portion of the 

 body and obtain development, one of their early effects is to pro- 

 duce, in that part, a number of small round bodies called nodules, 

 that are quite visible to the unaided eye, and which so invade the 

 texture of the affected organ or tissue as to quite change its ap- 

 pearance. These changes and their consequences, in their various 

 degrees, constitute what are known as the anatomical characteris- 

 tics of the disorder ; that is, the jyost-mortem appearances. 



As has just been shown, the disease may become seated in any 

 portion of the body, but it is very much more commonly met with, 

 in cattle, in the lungs and other organs within the cavity of the 

 chest. Other locations are upon the organs within the abdominal 

 cavity ; about the joints, especially the stifles or hocks, perhaps ; 

 in the udder ; and in the serous membrane covering of the brain. 



When the tubercle is young its color is a grayish white, and it 

 is semi-transparent ; a little later it becomes yellowish and opaque. 

 A single tubercle may be no larger than a number six shot, or it 

 may reach the size of a small pea, and 1ms a rather roundish form. 

 Tubercles very much more commonly exist in masses of a dense, 

 hard tissue, with a nodulated surface that is not at all easily sepa- 

 rated from the surrounding parts. 



As the tubercles grow older they commence to degenerate and 

 their appearance and character change considerably. Among these 

 changes is that known as " calcification," in which each nodule 

 becomes hard and feels like a little stone. When cut into it grates 

 under the knife, and the cut surface looks like particles of yellow, 

 greasy chalk, held together by fine bands of gristle. 



Another very common change is that one called " softening; " 

 this may or may not follow calcification. This commences at the 

 centre of the nodule, or the mass of them, and from there extends 

 towards the outer edge until the whole of the new growth has been 

 changed into the peculiar soft, so-called " cheesy " material. This 

 cheesy deposit varies a little in color and consistency under dif- 

 ferent circumstances. It may be grayish yellow and rather soft, 

 or a whiter yellow and harder. This depends upon whether or 

 not calcification has preceded it. As these masses grow older 

 there will often be centres of softening at various points within 

 them, forming cavities of greater or less extent, which contain 

 purulent matter. In the lungs and some of the glands, masses 

 often assume tremendous proportions. 



Another form of the tubercular deposit that is far from uncom- 

 mon in cattle is that in which the new growth springs up from the 

 serous membrane, lining the walls of the chest, and covering the 

 lungs themselves (the pleura) ; and from that lining the cavity of 



