CHAPTER II 



There is, however, an objection to the phagocytic 

 theory of acquired immunity, which at first sight 

 appears fatal, but which I think is capable of being 

 overcome. Pasteur found that in a man bitten by a 

 rabid animal, the onset of hydrophobia, or at any rate 

 its fatal termination, could in a great proportion of 

 cases be prevented by injecting into the tissues of the 

 patient emulsions made from the spinal cords of animals 

 dead of that disease, beginning with an emulsion from 

 a cord that had been dried for fifteen days in a closed 

 vessel over caustic potash, whereby it was in a great 

 measure bereft of moisture, and the pathogenic organisms 

 were probably quite destroyed, continuing day by day 

 with emulsions from cords of animals more and more 

 recently dead, from which, therefore, the moisture was 

 less and less thoroughly abstracted, and in which the 

 pathogenic life was less and less completely destroyed, 

 and ending with a cord which was absolutely fresh 

 and therefore virulently infective, as could be proved 

 by inoculating a susceptible animal with it and producing 

 fatal disease. It is to be presumed that the pathogenic 

 organisms were absent or almost absent from the first 

 injected, the old and thoroughly dried cord, but that 

 their toxins were present in it, and that in the fresher 

 cords, in direct proportion to their freshness, the 

 organisms were present as well as their toxins. 



216 



