348 TUBERCULOSIS AS A TYPE OF BACTERIAL DISEASE 



of their original bulk, and then passed through a Chamberland filter. 

 The brown and viscid filtrate is the tuberculin. Buchner and 

 Eomer pointed out that the proteins of other bacteria have a similar 

 effect upon tuberculosis, that is, cause a reaction with rise of 

 temperature. In 1897, Koch was able to improve his tuberculin, 

 and under the name "Tuberculin T. B." recommended a new 

 preparation. In point of fact, the new preparation takes three 

 forms, distinguished by the letters T. A. (alkaline tuberculin), T. 0. 

 (upper tuberculin, Germ, ober), and T. E. (residual tuberculin). T. A. 

 is extracted from a young and virulent culture of B. tuberculosis by 

 means of a one-tenth normal solution of caustic soda, and the 

 solution is filtered. The reaction on inoculation is intense, and may 

 be accompanied with abscesses. Accordingly, its clinical use is 

 open to objection. T. 0. and T. E. are prepared by vigorously 

 pounding in a mortar dried cultures of the tubercle bacilli and then 

 adding distilled water. The emulsion is thoroughly centrifugalised. 

 The clear, opalescent fluid collecting at the upper part of the tube 

 contains no tubercle bacilli, and constitutes in the first centrifugal- 

 isation T. 0. The debris or residuum of tubercle bacilli remaining at 

 the bottom of the tube is used for the production of T. E. This 

 residue is dried, triturated with distilled water, and centrifugalised 

 repeatedly until hardly any residue remains. Twenty per cent, of 

 glycerine is then added to both preparations for purposes of pre- 

 servation. T. E. alone is used clinically. 



The method of use is as follows : The animals are kept a day or 

 two in their byres, and the temperature is taken to standardise the 

 normal, which is generally about 102'2 F. The tuberculin is then 

 injected (30-40 centigrammes), and if the animal be tuberculous, 

 there is a rise in temperature of 1J to 3. The fever usually begins 

 between the twelfth and fifteenth hour after injection, and lasts 

 several hours. The more nearly the temperature approaches 104 F., 

 the more reason is there to suspect tuberculosis (Bang). The dura- 

 tion and intensity of the reaction, however, has not a direct relation 

 to the number or gravity of the lesions, but the same dose in healthy 

 cattle causes no appreciable febrile reaction. The tuberculous calf 

 reacts just as well as the adult, but the dose used is generally 

 smaller. 



Tuberculin injection has no bad effects on the secretion of milk, 

 either in quantity or in quality. The consensus of opinion of those 

 most experienced is that it does not lessen the secretion of milk in 

 dairy cattle, consequently they may be tested even when in full 

 milk without disturbing its secretion, unless it be during the few 

 hours of its absorption. It does not cause abortion in cows, or 

 sterility in bulls. 



It is the quickest and most reliable method of diagnosis of 



