TUBERCULOSIS. 339 



of many tups affected remain quite free from the disease, 

 provided they are not exposed to that cause — namely, cold — 

 which induces it in the progeny of those which have never 

 been affected. 



Treatment. — The cause or causes being removed, it will be 

 necessary to open the abscesses as soon as pus can be detected 

 in them, a matter of some difficulty, as their walls are very firm 

 and unyielding; how^ever, if by firm pressure with one hand, 

 and manipulation of the tumour with the other, the pus can be 

 felt fluctuating slightly, the operator need not hesitate, but make 

 a bold incision, press out the semi-fluid matter, and dress the 

 wound with some digestive, such as turpentine liniment. The 

 parts are to be kept clean, dressed antiseptically daily; the 

 wounds prevented from closing too quickly, and the animal fed 

 liberally. A small quantity of sulphate of iron in the food often 

 assists the recovery. A varying degree of swelling may exist 

 for a time after the wounds have healed. 



Abscesses about the throat in cattle are often supposed to 

 be tubercular, when in reality they are due to the actinomyces. 

 — (See Actinomycosis). 



PEEPARATION OF TUBERCULIN. 



For diagnostic purposes this preparation of the products of 

 the development of the bacillus in culture media has proved of 

 incalculable value, experiments having been made by scientists 

 in almost all parts of the world, and with the almost invariable 

 result of inducing a reaction in diseased animals only, healthy 

 ones, or those free from tuberculosis, remaining unaffected. 



A pure culture of tubercle bacillus is inoculated into broth 

 containing five per cent, of glycerine, and this is kept at a 

 temperature of about 98° F. in an incubator for six weeks. The 

 broth, now teeming with bacilli and rich in their products, is 

 sterilised by heating to 230° F. in the steam steriliser. This 

 kills the bacilli, while their products remain unaltered. It 

 is now evaporated until one-tenth only of the original volume 

 remains, and is filtered. 



METHOD OF INOCULATION AND EFPECTS OF TUBERCULIN. 



Upon the discovery of tuberculosis in a herd, all animals in 



