CUTANEOUS REACTION. 47 



As for the technique of injection, the inoculation is always 



Technique of given subcutaneously, and the back or breast is the best site 



Tuberculin for it. The dilution is made with physiological salt solution 



Injection. or o> ^ p er cent, carbolic solution, and it is advisable to make 



it immediately before the injection. 



In interpreting the result of the reaction one must exclude 



Value of rises of temperature due to extraneous influences such as 



Reaction. Angina, Influenza, etc. Furthermore there are individuals, 



especially hysterical ones, in whom any injection as such is 



apt to produce a rise of temperature. To guard against such a possibility an 



injection of physiological salt solution should be made and thus quiet any 



suspicion of error. 



The diagnostic use of tuberculin is indicated when one is 

 Indications, dealing with adults who present clinical symptoms, or clinically 

 suspicious symptoms of tuberculosis, but are devoid of the 

 presence of tubercle bacilli and temperature. 



Tuberculin is contra indicated in patients with high fever, 

 Contra- and during or shortly after hemoptosis or hematuria. In 

 indications, epilepsy, marked cardiac or renal affection, arteriosclerosis, 

 diabetes, and similar conditions, inoculation should be under- 

 taken only under the strictest indications and with great care. 



A positive general reaction means that the individual is infected with 

 tuberculosis, but does not throw any light upon the site, the extent, or the 

 prognosis of the infection. The focal reaction allows the diagnosis of the 

 position of the lesion. 



The Cutaneous Reaction. 



The cutaneous reaction was first introduced by v. Pirquet, who noticed 

 that by scarification of the skin and application of tuberculin, tuberculous 

 children would develop a distinct papule at this point, while in non-tuber- 

 culous conditions such a reaction would be absent. 



The Technique of the Cutaneous Reaction. 



"The patient's forearm on the inner side is cleansed with ether; two 

 drops of the pure undiluted old tuberculin are placed upon the skin about 

 10 cm. apart, and then the skin is scarified first between the two drops, for 

 the purposes of a control, and next within each of these drops. [A boring 

 scarifier devised for this, works very easily.] Finally a piece of cotton is 

 placed upon each of these drops and allowed to remain there for ten minutes, 

 after which the cotton is removed. A dressing is not necessary." 



Interpretations of the Reaction. 



Scarification of itself produces the so-called "traumatic reaction'' i.e., 

 a small wheel with a rose colored margin appears around each of the three 



