ESSAYS ON BACTERIOLOGY. 87 



ment of events, and to do our part in the coming work. 

 To this end two or three things are necessary: 



Pirst. Eemenibering that this new principle will 

 doubtless be brought forward and is being brought 

 forward in the treatment of other diseases, we must 

 guard against hasty enthusiasms based upon insuffi- 

 cient scientific experiment, and we shall certainly 

 have to guard against its commercial exploitation. 

 Already, unless the signs are misleading, the latter 

 evil is beginning to show itself. Plausible discover- 

 ers, with proprietary medicine schemes behind them^ 

 may create some stir among the unwary, for the nos- 

 trum business is at present flourishing even in the 

 profession. But surely there ought not to be much 

 difficulty in distinguishing science from mercenary 

 trickery. 



Second. We must expect and welcome and aid 

 scientific investigation and experiment along these 

 lines so clearly indicated as lines of progress. 



Third. We must, while this whole matter is^ as it 

 is, in the experimental stage, keep a clear view of the 

 facts, discriminating between things which are theo- 

 retical, imcertain and experimental, and those which 

 are demonstrated beyond question. Speaking again 

 of diphtheria only, the following seem to be the dem- 

 onstrated facts which we must accept: That there 

 is in this disease a germ which, being inoculated into 

 animals, will kill them. That this germ, being arti- 

 ficially cultivated, gives rise to a toxic substance or 



