TUBERCULINS 373 



disturbance more or less severe, and swelling and tume- 

 faction of tuberculous lesions (glands, ulcers, etc.), and 

 this reaction is made use of for diagnostic purposes 

 (see p. 399). By cautiously increasing the amount a 

 toleration is gradually induced, so that considerable doses 

 cause little or no disturbance. Injections of tuber- 

 culin tend to produce marked changes in the tuberculous 

 parts, leading to necrosis and exfoliation, with subsequent 

 healthy reaction and repair. This is especially seen in 

 cases of lupus ; by continued injections a marvellous 

 improvement results, so much so that a cure is apparently 

 effected ; but, unfortunately, when the treatment is dis- 

 continued the scar usually breaks down and the disease 

 returns. Nevertheless, a few cases have remained per- 

 manently healed. 



For treatment, the dose to commence with should not 

 be more than 0-0001 c.c., dilutions being made with 0-5 

 per cent, carbolic solution, and the dose is repeated when 

 all reaction has passed away and is gradually increased. 

 Tuberculin R, or tuberculin BE (see below), is now more 

 generally employed to commence with, and after a time 

 may be followed by a course of old tuberculin. 



Absolute alcohol precipitates the active principle of 

 tuberculin in the form of a whitish flocculent precipitate 

 which chemically consists of proteoses. This precipitate, 

 re-dissolved, is made use of in the ophthalmic reaction 

 (p. 400). Tuberculin applied to the scarified skin also 

 gives a cutaneous reaction in tuberculosis (p. 399). 



New Tuberculin (Syn. TR = tuberculin residual). 

 This is prepared from young and virulent cultures of the 

 tubercle bacillus. The growth is collected, dried in vacuo, 

 and triturated in a porcelain ball mill (p. 48). Of the 

 triturated material, 1 grm. is treated with 100 c.c. of 

 distilled water, and centrifuged. The supernatant liquid is 

 rejected, and the residue is collected, dried, again triturated, 



