THE PHENOMENA OF INFECTION 467 



excess of tuberculin which may be present. The information 

 obtained through the employment of the second instillation 

 in an individual who has previously failed to react is of 

 value in that it indicates that the body cells of the patient 

 are capable of producing a ferment which will split up 

 tuberculin, and consequently we should have obtained a 

 primary reaction provided the individual was actively tuber- 

 culous. Failure of the ophthalmo-reaction occurs under 

 the following conditions: (1) In early cases in individuals 

 who are incapable of producing the specific ferment. Such 

 individuals will fail to react to the second instillation. 

 (2) Normal individuals who are not afflicted with tuber- 

 culous disease will fail to react to the primary instillation. 

 They may, or may not, react to the second instillation, 

 depending on whether or not their body cells are capable 

 of producing the specific ferment. (3) Patients suffering 

 from acute tuberculous disease or advanced cases fail to 

 react to either the first or the second instillation. In these 

 cases the failure of the reaction is due to the exhaustion of 

 any specific ferment which may have been present through 

 the overwhelming of the system with tuberculin, or to the 

 accumulation of split products, as has been stated. 



While the importance of sensitization in connection with 

 the infectious diseases is not as yet thoroughly appreciated, 

 later investigations have been conducted largely along 

 these lines. Thus, sensitization is undoubtedly an important 

 factor in the treatment of bacterial diseases through the 

 employment of vaccine therapy. This is true whether the 

 vaccine employed consists of the whole bacterial cell or 

 the split products, such as those obtained after our method. 



The injection of foreign proteins as such into the body 

 always represents an abnormal condition. The symptoms 

 of sensitization following the administration of horse serum 

 in man may be divided into two classes, according to the 

 interval of time elapsing between the administration of the 

 serum and. the development of symptoms. In general, it 

 may be stated that symptoms of sensitization, provided they 

 occur at all, show themselves either very shortly after the 



