218 president's addkess. 



The practical outcome of the matter is that, although we can 

 scarcely hope at present to compass the complete destruction of 

 bacilli within the human body, we may at any rate do very much 

 to prevent their dissemination and to destroy them outside of the 

 organism. And it is possible that the practice of inoculation, 

 on which Pasteur's treatment of hydrophobia depends, may be 

 found applicable in other diseases. Hydrophobia has not indeed 

 been proved to depend upon the presence of a microbe, but the 

 general course of the disease leads to the belief in such an 

 origin ; and it seems certain that it is not the mere presence of 

 the microbes, but the presence of morbid products produced by 

 their growth which is really the proximate cause of disease and 

 death. Such is certainly the case, for instance, in diphtheria. 

 And it has been found that pure cultures of bacilli grown out- 

 side of the human body, lose gradually in the course of genera- 

 tions much of thair poisonous character. Acting upon this 

 knowledge Pasteur begins his treatment of hydrophobia by in- 

 jecting in the first place a weak culture of the hydrophobia 

 virus — whatever that may be — gradually increasing the strength 

 of the injection, time after time, until, as it is supposed, the 

 system acquires a tolerance of the poison, and in this way any 

 ill effects which might have resulted from the previous bite of 

 a rabid animal are nullified. "Whether the treatment has been 

 actually successful does not appear to me quite certain. It is 

 a matter which from its very nature must be difficult of proof, 

 while the possibility of inoculating a patient with so dreadful a 

 disease is a thing almost too hideous to contemplate. 



Leaving the subject of disease, it is interesting to note that 

 Bacteria seem also to be the cause of the colour-stains which 

 frequently make their appearance in decaying substances such 

 as bread, milk, and gelatine ; and that they are probably to a large 

 extent the active agents in the phenomena of phosphorescence. 



