ANAPHYLAXIS AND IMMUNITY 257 



ous protein we can pass through the anaphylactic to the succeed- 

 ing stage of immunity. Now the characteristic of a true bacterial 

 (as distinct from an antitoxic) immunity is that the body fluids 

 gain remarkable digestive or fermentative powers. Any one who 

 has observed Pfeiffer's phenomenon — has seen living typhoid or 

 cholera organisms swell up and dissolve like pieces of sugar in 

 the serum of a highly immunized rabbit or guinea-pig — cannot 

 fail to be impressed by the extraordinary digestive powers that 

 have been acquired by the body fluids through this process of 

 immunization. 



Everything here indicates that we deal with proteoclastic 

 enzymes. Only now, in the immune animal, the process no longer 

 leads to acute poisoning. I admit that more than one explanation 

 may be sought and given for this fact, but, choosing the simplest, 

 we see here a further evolution of the same process, namely, 

 the development by the organism of further enzymes which 

 disintegrate the poisonous moiety, and so carry on the degrada- 

 tion of the foreign protein to a further and harmless stage. It 

 is pleasant to think that we owe to one of our own workers, 

 Dr. Fraser B. Gurd, the first experimental evidence of the co- 

 existence of these two orders of enzymes (lysins) in the immune 

 animal. 1 As he points out, it is not that the earlier enzymes are 

 completely replaced : they are still active and indeed abundant, 

 and evidence of the presence of these sensitizing bodies can be 

 obtained in immune animals. But after they have broken 

 down the specific protein with the production of the poisonous 

 substance, this is immediately acted on by the new enzyme and 

 rendered innocuous. 



To me it is not a little curious that Abderhalden, Thiele, and 

 Embleton, and the other workers in this territory, while familiar 

 with the existence of the great numbers of individual enzymes 

 that are to be isolated from the organism, have not taken up and 

 considered this probability of, or recognized the indications 

 pointing to, the production of a succession of progressively more 

 specific and more active enzymes in the development of the 

 immune state. 



1 Amer. Jour. Trop. Dis. and Preven. Med. i., 1914, 776 ; Jour. Med. Fes. 

 xxxi., 1914, 205. 



