318 BACTERIOLOGY. 



lying the establishment of artificial immunity apply as 

 well to this disease as to a number of others. They have 

 shown that by the use of cultures of the plague bacillus 

 that had been killed by heat animals may be rendered 

 immune from infection by the virlent living organism. 

 They have also shown that the serum of the blood of 

 these animals is not only capable of conferring immunity 

 upon other animals into which it is injected, but it has 

 curative properties as well, providing it be employed at an 

 early stage of the disease. In 1896 Yersin 1 used the 

 serum of artificially immunized horses in the treatment 

 of plague in human beings. Of 26 persons (3 in Canton 

 and 23 in Amoy, China) who received injunctions of the 

 serum during the early stages of the disease, in no case 

 later than the fifth day, only 2 died. Comparing this 

 mortality of 7.6 per cent, with the mortality of 80 per 

 cent, among persons in this epidemic who were treated 

 in other ways, he feels justified in regarding the method 

 as worthy of consideration. 



Subsequent investigations, notably those of the Pest 

 Commission of Germany, Austria, and Egypt, as well 

 as those of the Institutes for Infectious Diseases at Ber- 

 lin, Berne, and the Pasteur Institute of Paris, 2 have con- 

 tributed much additional information of importance to 

 this subject. They confirm the original views upon 

 the protective or prophylactic value of the anti-plague 

 serum, but demonstrate that as a therapeutic agent it is 

 of but limited usefulness. 



i Annales de Tlnstitut Pasteur, 1897, p. 81. 



2 The important literature bearing on this subject is appended to 

 the report of Kolle, Hetsch, and Otto (Zeitschr, f. Hygiene, Bd. 88, 



p. 368). 



