PHENOMENA OF SUPERSENSITIVENESS 297 



heading of the production of hypersensitiveness, and of immunity 

 phenomena. 



(1) Phenomena of Supersensitiveness. (a) The Original 

 Tuberculin Reaction. This can be manifested with any of the 

 tuberculin preparations. Thus, if '25 c.c. of "old" tuberculin 

 be hypodermically injected into a healthy individual, there occur 

 in three or four hours malaise, tendency to cough, laboured 

 breathing and moderate pyrexia, all passing off in about twenty- 

 four hours. If, however, only O'Ol c.c. be injected into a tuber- 

 cular subject, similar symptoms but in a much more aggravated 

 form (the so-called tuberculin reaction^ arise, and if there be 

 present a local tubercular focus e.g., lupus there occurs round 

 it a definite inflammatory reaction with, it may be, ulceration. 

 Similar phenomena of " Supersensitiveness " are produced by the 

 injection of almost any foreign proteid into an animal. The 

 subject will be discussed in the chapter on Immunity under the 

 heading of Anaphylaxis, and it may be said that anaphylaxis 

 is observed when living or dead tubercle bacilli are injected 

 into healthy animals. The tuberculin reaction is much used in 

 diagnosis and, in addition to the methods just described, the 

 following special modifications are frequently used for this 

 purpose : 



(b) The Cutaneous Tuberculin Reaction of von Pirquet and 

 the Ophthalmo-reacti&n 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 pre- 

 vent 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 



