180 INFECTION AND IMMUNITY. 



The Mac- MacFadyen, by grinding large masses of typhoid 

 IK" hod! bacilli and other organisms which had been rend- 

 ered brittle by the temperature of liquid air, 

 obtains from these organisms a toxic cell juice. 

 The efficiency of the antitoxins which he is said 

 to obtain by such immunization has not been 

 demonstrated practically. It seems improbable 

 that immunization with such "toxins" will yield a 

 serum differing in properties from that obtained 

 by immunization with the living organisms. 

 Accidental Toxic substances obtained from bacteria by the 



Toxic 



substances, action of strong chemicals and extracting fluids, 

 may not represent the essential toxic substance of 

 the organism, but perhaps some disintegration 

 product which happens to be toxic. 



It is, of course, common knowledge that an anti- 

 toxin is the blood serum of an animal, after the 

 latter has been rendered highly immune by re- 

 peated injections of the corresponding toxin. The 

 horse is chosen for immunization because of its 

 marked ability to yield antitoxins (diphtheria, 

 tetanus), because of its size, withstanding much 

 loss of blood, and because of the readiness with 

 which it submits to manipulation. 



preparation Manufacturing plants which produce antitoxins 

 toxins. an ^ other antiserums on a large scale have splen- 

 didly equipped stables, which are kept in the 

 optimum hygienic condition, and from which rats 

 in particular are rigorously excluded. 2 The horses 



2. The importance of this is very great if, for example, 

 horses are receiving injections of some virulent living 

 micro-organism (as the plague bacillus). In this case 

 living micro-organisms reach the general circulation, and a 

 rat having bitten the animal could well contract the 

 plague and be an evident source of danger, not only to 

 other animals, but to the community at large. Even fly- 

 proof stalls are properly instituted in such cases. 



