450 THE TUBERCLE BACILLUS GROUP 



first signs appearing in from four to twenty-four hours. In scrofulous 

 children small raised follicular swellings commonly appear around the 

 central specific area, the so-called scrofulous reaction. It should be 

 remembered that a second injection of tuberculin in the same area on 

 the same arm following an initial negative reaction may be positive. 

 This is not an indication of infection, however; it is rather a mani- 

 festation of local sensitization. 1 



(c) The Percutaneous Test (Moro). Moro has modified the von 

 Pirquet test in such a manner as to exclude the traumatism incidental 

 to scarification. This is accomplished by rubbing into the skin of the 

 abdomen or the chest an ointment made of 5 c.c. of old tuberculin 

 mixed intimately in 5 grams of anhydrous lanolin. In practice a bit 

 of the ointment one-half a centimeter in diameter is rubbed over an 

 area of about four square inches for about half a minute. The oint- 

 ment is left on the skin to absorb gradually. A positive reaction 

 consists in the development, usually within twenty-four to forty-eight 

 hours, of a number of small red papules within the area of inunction. 

 Ordinarily but a few papules are formed; less commonly a consider- 

 able crop appear. Rarely the skin in the immediate area is reddened 

 and there may be slight itching. The papules are few in number in 

 a mild reaction, usually from two to eight or ten; they are red and from 

 1 to 2.5 mm. in diameter. A moderate reaction is characterized by 

 many red papules, from 10 to 100, which are rather closely crowded 

 together and usually from 0.25 to 2.5 mm. in diameter. The inter- 

 papular areas of skin may or may not be reddened. If the skin is 

 reddened it frequently itches somewhat. In a severe reaction papules 

 appear within a few hours after inunction, many in number with a 

 markedly hyperemic background. Itching is a very disagreeable 

 feature of a severe reaction. 



(d) The Detre Test. Human tuberculin is rubbed into one arm 

 and bovine tuberculin is rubbed into the other, using preferably the 

 cutaneous reaction of von Pirquet. It was supposed by Detre that 

 the tuberculin reaction elicited will indicate the type of infection, 

 whether it be of the bovine or the human bacillus. This test is of 

 doubtful value for this purpose. 



(e) The Ophthalmo Reaction of Calmette. One drop of a 1 per cent, 

 dilution of old tuberculin purified by precipitation with alcohol is 

 instilled in the conjunctival sac. In tuberculous subjects this instil- 



1 The von Pirquet reaction is usually negative in tuberculous children during the 

 acute stage of measles, and occasionally in whooping-cough. 



