42 VACCINE AND SEEUM THEEAPY 



symptoms as before, but on autopsy the peritoneal 

 cavity shows a j)rofuse serous exudate, which contains 

 innumerable actively motile micro-organisms. In 

 this case we find that not only has the serum lost its 

 neutralising property, but it has also lost its bacteri- 

 cidal and phagocytic properties as well. 



By formulating the above theory, I am perhaps 

 laying myself open to severe criticism, but by a 

 careful study of the facts revealed by Pfeiffer and 

 Wasserman's experiments and the clinical observa- 

 tions I have previously mentioned, this seems the 

 only possible explanation of the phenomena occurring 

 within the body of an animal suffering from a virulent 

 bacterial invasion. 



Reviewing all the above facts and theories, let us 

 see what relation they bear to the prevention and 

 treatment of disease. Take first those diseases 

 caused by bacteria which secrete true soluble toxins. 

 It is by the action of these toxins upon the sensitive 

 physiological cells of the animal that the disease 

 manifests itself. In veterinary medicine the com- 

 monest example of this class of disease is tetanus. 

 Tetanus-immune serum is able to neutralise tetanus 

 toxin unit for unit, but this neutralisation must be 

 accomplished before the toxic atom attaches itself to 

 the cell receptors ; therefore, it is necessary that 

 antitetanic serum must have a chance of neutralising 

 the toxins of tetanus bacilli while they are freely 

 circulating in the tissues — in other words, the specific 

 use of the antiserum is that of a preventative. At the 



