lo Veterinary Medicine. 



produce antiprecipitins, immune body secures anti-immune body^ 

 toxins produce antitoxins, cytotoxins produce anticytotoxins, sper- 

 motoxin invokes antispermotoxin, neurotoxtin produces antineuro- 

 toxine. The operation of each poison rouses the leucocytes and 

 body cells to elaborate its special antidote. The antibody for 

 one species of animal, however, or for one poison, is not therefore 

 effective in another animal species nor for another poison. The 

 antibodies cannot be used interchangeably for different diseases 

 or animals. 



Immunization by toxins and ptomaines is a means of rousing' 

 the animal cells of the subject injected to the production of the 

 requisite toxins, ptomaines, etc., {antibodies') to prevent the 

 disease from which the poison was drawn. The production of 

 the antibodies may be more or less abundant and permanent, and 

 thus immunization is likely to be more or less perfect and endur- 

 ing. These antibodies may often be cultivated in the bodies of 

 animals which are not naturally susceptible to the disease (which 

 are already innately charged with antibodies) and which can there- 

 fore bear much larger doses of the poison, and in this way the most 

 potent defensive serum may be secured. Thej may, on the 

 other hand, be rendered ineffective on the animal injected, by 

 reason of the absence of the intermediate bodies by which their 

 connection is established, by reason of a special susceptibility to- 

 the pathogenic microbes or their toxins, or by reason of the 

 presence of acids or other bodies which increase susceptibility to 

 microbes or toxins. 



Two other considerations enter into the question. If the 

 unaltered serum of an infected animal is used containing the 

 living microbe, there is some danger of the survival of the latter, 

 and of its propagation to other susceptible animals, thus starting^ 

 an epizootic. Again if the serum is devitalized by heat, oxygen 

 under pressure, or otherwise, there is the danger of destruction 

 of the antibodies, or of some of the intermediate bodies by which 

 their preventive action is established. The devitalized serum is 

 the safe agent to use, but it is not in every disease that it can be 

 secured by available methods, and therefore sterile sera cannot 

 always be availed of. 



Protection by antibodies produced in the system of a normally 

 immune animal which has been made still more resistant, or 



