88 ESSAYS ON BACTERIOLOGY. 



substances, which also will kill. That this germ or 

 this toxin, being introduced according to a certain 

 method and in progressive quantities into certain ani- 

 mals, there is developed in those animals a progres- 

 sive resisting power to the germ or toxin, reaching an 

 astonishingly high degree, and lasting for a varying 

 but usually limited time. That the transfer of the 

 blood-serum of such animals to those previously sus- 

 ceptible to diphtheria does afford them almost at once 

 a practically absolute, though temporary, immunity 

 against or cure of diphtheria. That, in a word, it is 

 thus possible to absolutely control otherwise fatal ex- 

 perimental diphtheria intoxication and diphtheria in- 

 fection in animals, and that without apparent harm. 

 That the longer the infection has run, the less certain 

 are the results, a point finally being reached when the 

 treatment may become impracticable and of little 

 avail. Experience with this treatment, applied to ac- 

 cidental human diphtheria, seems to indicate that hu- 

 man beings and the lower animals react in the same 

 way to the antitoxin serum therapy. But the truth 

 of this proposition is still t-o be fully and finally dem- 

 onstrated. AVe must wait for the verdict of time be- 

 fore we can say of men as of animals : We know that 

 a specific for diphtheria has been found. While we 

 wait for and help to hasten the solution of the qaes- 

 tions, let us hopefully keep in mind a clear view of 

 the established facts. 



