PHENOMENA OF SUPERSENSITIVENESS 285 



and a casting off of the tubercular mass, when this is possible, 

 as for instance in the case of lupus. The bacilli are, it was 

 shown, not killed in the process. 



The hopes which the introduction of tuberculin raised, that a 

 curative agent against tuberculosis had been discovered, were 

 soon found not to be justified. It was very difficult to see how 

 the necrosed material which was produced and which contained 

 the still living bacilli, could be got rid of either naturally, as 

 would be necessary in the case of a small tubercular deposit in 

 a lung or a lymphatic gland, or artificially, as in a complicated 

 joint-cavity where surgical interference could be undertaken. 

 Not only so, but the ulceration which might be the sequel of the 

 necrosis appeared to open a path for fresh infection. Soon facts 

 were reported which justified these criticisms. Cases where 

 rapid acute tubercular conditions ensued on the use of tuberculin 

 were reported, and in a few months the treatment was practically 

 abandoned. 



(b) The Cutaneous Tuberculin reaction of von Pirquet and 

 tJie Op/tt/tal mo-reaction of Calmette. In recent times the diagnosis 

 of tuberculosis has been considerably aided by the introduction 

 of these two tests. Both are essentially of the same nature, and 

 depend like the original tuberculin reaction on the sensitiveness 

 of the tissues of tubercular patients to tuberculin. 



The cutaneous test is carried out as follows : The skin, usually 

 that of the flexor aspect of the forearm, is well cleansed with 

 ether and then allowed to dry. Two drops of tuberculin are 

 placed on the prepared surface about four inches apart, and then 

 midway between the two drops a small spot is scarified with a 

 small metal bore constructed for the purpose. This serves as a 

 control, any reaction which follows in it being merely a traumatic 

 one. Similar scarification is effected through the drops of 

 tuberculin, so that the scarified spots are exposed to its action. 

 Small portions of cotton wool are placed over the drops to 

 prevent the tuberculin from running off, and the latter is allowed 

 to act for ten minutes. After that time the cotton wool is 

 removed ; no dressing is required. In the process of scarification 

 only the epidermis should be injured and blood should not be 

 drawn. The "old" tuberculin of Koch is that used. In the 

 case of a positive reaction an inflammatory redness and swelling 

 make their appearance round the sites of tuberculin inoculation, 

 generally within a few hours, and at the end of twenty-four hours 

 there is a distinct inflammatory papule about half an inch in 

 diameter, with a somewhat paler centre like a spot of urticaria; 

 sometimes in the centre there are minute vesicles. The maximum 



