PAPERS OX MEDICINE AND PUBLIC HEALTH 329 



extension of the lesion and active tuberculous 



. of the University of California, attempt- 

 ed to show that the appearance of a posit. a re- 

 action to typhoidin is an indication of immunity to ty- 

 phoid fever. This, however, is not exactly the > 

 since this reaction : disappears at a time after 

 infection or vaccination when immunity is still known to 

 exist. More recently an intracutaneous method of diag- 

 nosis of whooping cough 7 during the first weeks of this 

 was advocated. This, however, has been 

 shown not to be a specific reaction. In fact attempts to 

 duplicate published results by Hull and Xauss ; show con- 

 clusively that identical reactions may be obtained 

 through the injection of quite different inciting sub- 

 stan' - 



Within a few months also an intracutaneous method of 

 diagnosis of scarlet fever based on recent investigations 

 of the etiology of this disease has been published'. This, 

 if satisfactorily confirmed, will prove to be a great boon 

 not only to the practicing physician but also to the health 

 administrator. It may be pointed out further that the 



— ibilities of development in this field have not by 

 any means been exhausted. The exact and rapid labora- 

 tory diagnosis of both infection and immunity in many 

 other communicable diseases offers sufficient stimulus 

 to both investigator and hygienist as to warrant the most 

 exhaustive researches. 



As a recent development of the application of this 

 principle, the Schick test in diphtheria deserves special 

 mention. Similar to most allergic reactions in man. this 

 is not of the nature of anaphylaxis. In fact, it may be 

 looked upon as a comparatively simple case of a biolog- 

 ical chemical reaction confined for the most part to the 

 of injection of the active diphtheria toxin. The 

 Schick test runs quite a definite course, which will be 

 illustrated in connection with a series of lantern slides, 

 which are to lie thrown upon the screen, showing various 

 local manifestations of allergic skin reactions. 



As aids to the diagnostician, these various local mani- 

 festations of allerary may be divided into two creneral 

 - - ■ namelv, those which serve 3 indices 



