THE PHENOMENA OF INFECTION 457 



or tissues in which the infecting agent is located. In acute 

 miliary tuberculosis and in typhoid fever, both conditions 

 arising from a bacteremia caused by different organisms, 

 the symptoms are only too frequently identical, and it is 

 only by bacteriological methods, a suggestive history, or 

 the finding of a preexisting tuberculous focus in some part 

 of the body that a differential diagnosis may be reached. 

 A cholecystitis is the same, not only in symptomatology, 

 but frequently in gross pathology as well, whether the 

 infecting organism be the pneumococcus, the streptococcus, 

 the colon, or the typhoid bacillus. The most skilful diag- 

 nostician cannot tell from the symptoms alone the specific 

 bacterial cause of a meningitis. 



During the period of incubation of an infectious disease, 

 the infecting organism supplies the ferment, the body pro- 

 teins constitute the substrate, the process is essentially 

 constructive, no poison is set free, and there are no recog- 

 nizable clinical symptoms. During the active progress of an 

 infectious disease, the body cells supply the ferment, the 

 infecting organism constitutes the substrate, the process is 

 essentially destructive, the protein poison is set free, the 

 symptoms of disease appear and life is placed in jeopardy. 



Our w^ork seems to show that the body cells, when over- 

 whelmed with a foreign protein of the blandest kind such 

 as egg-white may fail to function and death may result. 

 There is no reason for suspecting that in these cases there 

 is any cleavage of the foreign protein or the liberation of 

 any poison. The body cells are simply clogged with the 

 foreign protein and fail to function. We are not sure that 

 this phenomenon has any parallel in the infectious diseases. 

 There is, however, something closely related to it in cholera 

 infantum, cholera nostras, and Asiatic cholera. 



We have already referred to the fact that ferments may 

 be modified in their activities. These modifications may 

 be so radical that it is generally believed that cells may be 

 trained, as it were, to develop new ferments. There can 

 be no doubt that change in environment does alter activity 

 as manifested, through the ferments. As we have stated, 



