n6 BACTERIOLOGY 



ment the dosage is kept low to avoid reaction, gradually 

 increasing as tolerance is established. In its diagnostic 

 use quite large doses are used for the purpose of bring- 

 ing about the very symptoms it is sought to avoid in its 

 employment as a remedial measure. 



Methods of Administering the Tuberculin Test. By 

 Injection. Old tuberculin is used, and in a weak patient 

 the dose may be about ^ mg., while a robust one should 

 be given as high as i mg. The dose is injected under 

 the skin of the back, observing the usual antiseptic 

 precautions. Should no rise of temperature occur, 

 another injection of double the amount of the first dose 

 is given on the third day. In robust patients even 

 larger doses may be given, such as 5 or 10 mg. at the 

 second or third dose, when, if no reaction occurs, the 

 patient may be considered free from active or progress- 

 ive tuberculosis. A very slight rise of temperature, if 

 accompanied by a local reaction, should be considered 

 positive. 



Cutaneous Reaction, Von Pirquet's Test. This form 

 of the tuberculin test consists of the application of 

 tuberculin to the skin by scarification. The inner side 

 of the forearm is washed with ether. Two drops of old 

 tuberculin are dropped upon the arm about 4 inches 

 apart. The skin is then scarified first between the two 

 drops, then within each of the drops with a special scari- 

 fier furnished for the purpose, the amount of abrasion 

 being sufficient to form a scab, but under no circum- 



