38 ADAPTATION AND DISEASE 



of the characters of the typus bovinus. Vincent is so careful 

 an observer that I do not like to reject his work. At the same 

 time I confess I should feel more satisfied had it been confirmed 

 by other workers. 1 



It is here in London, at University College, that what appears 

 to be the crucial demonstration has been afforded by a pair of 

 well-known and capable workers, and that by the employment 

 of a most ingenious method. Every medical man nowadays 

 is familiar with the name at least of anaphylaxis, even if he is 

 unable to grasp the nature of the paradoxical phenomenon — 

 the phenomenon, that is, of inducing not immunity, but the 

 reverse condition of increased susceptibility to foreign proteins, 

 by the injection of the same into the tissues. If minute doses 

 of any protein foreign to the organism — even if it be so harm- 

 less a one as egg white — be introduced parenterally, i.e. into 

 the tissues as contrasted with alimentary canal, and some eight 

 days or more later a second and larger dose be similarly intro- 

 duced, instead of tolerance having been established, the very 

 reverse condition is found to have been set up. Grave con- 

 stitutional symptoms supervene, and in animals like the guinea- 

 pig death may ensue with startling rapidity in the course of a 

 minute or two. I believe that I was the first to point out, 2 

 and that with Professor Vaughan's entire concurrence, that 

 these phenomena are explained by that observer's most remark- 

 able studies upon the dissociation products of proteins. As he 

 has abundantly demonstrated, 3 treated with alcohol rendered 

 alkaline by the addition of caustic soda, all true proteins, includ- 

 ing the bodies of bacteria (or their protein constituents), become 

 dissociated into an intensely toxic and a non-toxic moiety. 

 The explanation, therefore, of anaphylaxis — and this is confirmed 

 by Abderhalden's later work — is that it is the first stage in the 

 production of immunity : the organism has reached the stage 

 of producing enzymes which dissociate the proteins into a toxic 

 and a non-toxic moiety, but has not attained to the later stage 

 in which specific enzymes are developed, dissociating the toxic 



1 It deserves note that the bacteriology of soil bacteria has been worked out 

 very imperfectly, and it is evident that more than one species has been described 

 as B. megatherium. It may therefore be that the B. megatherium of other 

 workers is not the same organism as that employed by Vincent. 



2 Principles of Pathology, 1st ed. i., 1908, p. 509. 



3 See Vaughan, Protein Split Products. Philadelphia, Lea and Febiger, 1913. 



