TUBERCULIN 51 1 



which is sterilised by heat and filtered through porcelain, so that it 

 contains no living germs, and therefore cannot produce tuberculosis 

 in animals injected with it It has, therefore, no effect on healthy- 

 animals ; in some cases the disease is aggravated by it when it 

 exists, but it cannot be produced by it. The lymph must not be 

 exposed to sunlight ; it must not be frozen, and must be kept well 

 corked to exclude air. 



Koch's "old tuberculin" is made from glycerine veal broth 

 cultures of B. tuberculosis by means of evaporation and precipita- 

 tion with alcohol. The liquid cultures are thus concentrated to one- 

 tenth of their original bulk, and then passed through a Chamber- 

 land filter. The brown and viscid filtrate is the tuberculin. 

 Buchner and Romer 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. R." recommended 

 a new preparation. In point of fact the new preparation takes 

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

 T. O. (upper tuberculin, Germ, ober), and T. R. (residual tuberculin). 

 T. A. is extracted from a young and virulent culture of B. tubercu- 

 losis by a 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. O. and T. R. 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. O. The debris or residuum of tubercle bacilli remaining 

 at the bottom of the tube, is used for the production of T. R. 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. R. alone is used clinically. The dose is -5^ milli- 

 gramme gradually increased up to 20 milligrammes. 



How tuberculin is used. — 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. 



