ANTHRAX. 347 



is common, thousands of animals have been inoculated, and it 

 is thought that the lives of a great number have been thus pro- 

 tected. It has been found by experience that the protection 

 thus acquired is not very lasting, and that animals must be 

 inoculated about once every year if they are to be thoroughly 

 protected. This, of course, reduces the value of the inocula- 

 tion, and confines its use to special localities or special seasons 

 when the disease is rife. The vaccine also deteriorates rapidly 

 and is only efficacious when fresh. For these reasons the 

 method of inoculation is not used so widely as at first, and has 

 not been used to any considerable extent in the United States. 

 This discovery of Pasteur had, however, an importance ex- 

 tending far beyond its relation to anthrax. It was the dis- 

 covery of a new principle, and not simply the discovery of a 

 new fact. If it is possible to produce immunity by the use of 

 weakened cultures, and if pathogenic bacteria may be weak- 

 ened by simple laboratory methods, why could not the same 

 principle be applied to all other infectious diseases ? It was 

 immediately perceived that this discovery marked a new epoch 

 in the methods of studying and handling diseases, and it was 

 inevitable that the same principle should be extended to many 

 other diseases. It is not in place here to follow this discovery 

 into other fields and explain its successful and non-successful 

 application to other diseases. It may simply be stated that 

 this famous experiment pointed out the line along which bac- 

 teriologists have been working in the last two decades, and 

 are still working, in their endeavors to find the proper method 

 of mastering some of our most serious human diseases. The 

 results have borne much fruit and we may confidently expect 

 even greater results in the future. 



