PEACTICE OF MEDICINE AND HYGIENE 



step in animal experimentation, man himself 

 is the animal observed. There are a number 

 of instances on record of persons having taken 

 into their stomachs, experimentally, acciden- 

 tally, and with suicidal intent, cultures of ty- 

 phoid bacilli which were being grown artifi- 

 cially in glass tubes in the laboratory, or in the 

 form of dejecta, and developed typhoid fever. 

 Furthermore, Brieger has isolated the chemical 

 substance secreted by the typhoid bacillus, and 

 by injecting this substance into animals he 

 has produced the fever, nervous symptoms, and 

 other manifestations characteristic of the dis- 

 ease. 



The most hopeful treatment of typhoid fever 

 is being worked out by animal experimenta- 

 tion. Prompted by the brilliant results ob- 

 tained from the use of diphtheria antitoxin, 

 Pfeiffer, Fraenkel and Manchot prepared a 

 sterilized liquid from the cultures of the 

 typhoid organism and secured encouraging re- 

 sults from its use. Then Hughes and Carter 

 used the blood serum of convalescent patients 1 , 

 which experiments were followed by Kleni- 

 perer and Levy who used the blood serum of 

 dogs after inoculating them with pure cultures. 

 They found this serum capable of rendering 



61 



Vaccination 



against 



typhoid. 



