" REACTIONS AND SIMILAR PHENOMENA 303 



reaction is caused by large doses. Thus Wassermann records a 

 case in which 300 milligrammes caused no reaction. The patient 

 had been treated for a year, the dose being gradually increased. 

 It appears, too, that by careful treatment of animals an antituber- 

 culin can be produced which has the power of inhibiting the effects 

 of tuberculin in tuberculous animals. It has, however, little or 

 no effect in the treatment of the disease another proof that tuber- 

 culin is not the specific toxin. 



Quite recently important modifications have been introduced in 

 the diagnostic application of tuberculin. Von Pirquet's reaction, 

 or the cnti-veaction, is elicited by placing a drop of tuberculin 

 (undiluted or a 25 per cent, solution) on the skin, and performing 

 scarification just as for an ordinary Jennerian vaccination. It is 

 advisable to make a similar control scarification without using 

 tuberculin in order that the lesions may be compared. The 

 simple inoculation shows a little redness, which soon disappears. 

 That made with tuberculin does the same if the patient is not 

 tuberculous. If he is, a small red papule is formed, which increases 

 for three or four days and disappears in a week or so. 



Calmette's method, the ophthalmo - reaction, is obtained by 

 instilling one or two drops of diluted tuberculin into the conjunc- 

 tival sac. He recommends the use of old tuberculin which has 

 been precipitated with absolute alcohol and redissolved in distilled 

 water, as being less irritating and less likely to cause a pseudo- 

 reaction in a non-tuberculous patient. The reaction in this case 

 consists of a mild attack of conjunctivitis, lasting twenty- four 

 hours, and accompanied by redness and swelling of the caruncle 

 and a small amount of mucoid secretion. The reaction should be 

 over in twenty-four hours, but in some cases undesirable results 

 have occurred from a secondary infection with organisms capable 

 of causing a more severe conjunctivitis or keratitis. For this 

 reason the test should be used with care, if at all. 



These tests are most applicable in children, since in adults the 

 frequency of cured tubercle, also leading to hypersensitiveness, 

 may lead to reactions where there is no clinical tubercle, or the 

 patients may be more or less immune. 



- Reactions are given in other diseases, the most important being 

 glanders. Mallein is a fluid obtained from cultures of B. mallei 

 exactly as tuberculin is obtained from tubercle bacilli. It is non- 

 toxic to normal animals, but it causes a febrile reaction in those 

 infected by glanders, even if there is but a small latent lesion. 



