598 ANAPHYLAXIS IN RELATION TO INFECTION AND IMMUNITY 



3. The late reaction, which appears after twenty-four hours and de- 

 velops and recedes slowly. These last two types are believed to occur 

 in patients having inactive lesions. 



4. The cachectic reaction, which is characterized by infiltration with 

 little or no redness. This type is common in the late stages of tubercu- 

 losis. 



5. The scrofulous reaction, which is characterized by numerous small 

 elevated nodules, which may also appear on the extremities and trunk. 

 This reaction is peculiar to children and rare in adults. 



THE CONJUNCTIVA!. TUBERCULIN REACTION (CALMETTE) 



Variety of Tuberculin Used. A 1 per cent, solution of Koch's old 

 tuberculin is now generally used, as it is quite reliable, least expensive, 

 and the results that follow its use are more regular than those ob- 

 tained with purified tuberculin (0.5 to 2 per cent, aqueous solution). 



Method of Conducting the Test. The conjunctive of both eyes 

 are inspected to ascertain if there is any evidence of disease and if they 

 are strictly comparable in color. The lower lid of one eye is drawn for- 

 ward to form a little pouch, and the patient is directed to look upward ; 

 one drop of a 1 per cent, dilution of old tuberculin is then applied from 

 an ordinary eye-dropper to the lid at the inner canthus. Profuse 

 lacrimation impairs the test, and it is useless to attempt it with weeping 

 or resisting children. If no reaction is apparent and it is still desired 

 to further the test, a drop of a 5 per cent, dilution may be placed in the 

 opposite eye. 



The Reaction. In a positive reaction the conjunctiva begins to 

 redden in from six to eight hours, and reaches its maximum in from 

 twenty-four to forty-eight hours, and then rapidly subsides and dis- 

 appears in from four to six days. In mild reactions the inner canthus 

 is the seat of the most marked changes. Positive reactions have been 

 classified as follows: 



+ Reaction: Definite palpebral redness. 



Reaction : More marked palpebral redness with secretion. 



Reaction: Palpebral and bulbar redness with subjective 

 symptoms and well-marked secretion. (See Fig. 124.) 



Precautions. On account of severe reactions and the danger of 

 inflicting permanent injury on the cornea there is a growing tendency 

 to regard this reaction with disfavor. Hamman and Wolman, however, 

 believe that, with proper precautions, these risks may be minimized, 

 if not completely avoided; they believe, moreover, that the risk in- 



