president's address — SECTION L. 285 



Here again, as in the case of many other cherished theories 

 related to immunity, Bordet, who may almost be termed Bordet 

 the iconoclast, has submitted this theory and the experimental 

 work on which it stands to^ a searching scrutiny, and however 

 mnch we may still cling to Friedberger's conception, it must be 

 admitted that it cannot remain as a generalization covering the 

 whole field. 



Fi-iedberger and, indeed, the great majority of those workers 

 investigating anaphylaxis have assumed that the source of the 

 po'iso'/i uYis the antigen; that from it alone, whether by a " feT- 

 ment " or by complement and antibody, the poison was derived. 

 An obvious difficulty occurs at once, for it is surely very re- 

 markable that no matter what the antigen, whether serum, blood 

 cells, bacteria of different kinds, egg albumen, &c., the symptoms 

 produced and the 'post-ni.ortem appearances are always the same. 

 As Bordet points ooit, some oi Friedberger's own eixperiments show 

 that an antibody is not of necessity present in all cases of anaphy- 

 laxis. What is essential in all cases apparently is the presence 

 of fresh serum, if the' anaphylactic poison is to be produced, and 

 Bordet asks with insistence, may it not be that this serum is 

 indeed the source of the toxin ? So Bordet and Gengou have 

 suggested that the origin of the anaphylactic toxin is not the 

 antigen, but the serum ot the^ animal affected. 



By this theory the poison is preformed in the blood, and only 

 prevented from acting by a physiological equilibrium which is 

 upset at the time of the second injection by the adsorption of 

 some substanee necessary tO' keep it stable. An experiment cf 

 Bordet's (1913) lends support ^o this view, for he was able to 

 show that anaphylactic shock can be produced without using any 

 antigen. Ordinary agar purified so as to retain no trace of pro- 

 tein, dissolved in saline, and mixed with an excess of fresh guinea 

 pig serum, will, when injected intravenously into a normal guinea 

 pig, cause shock and death in a few minutes. 



Further the agar solution if given in sublethal doses will pro- 

 duce a condition of anti-anaphylaxis. 



These results have been confirmed by Novy and de Kruif , Zunz 

 (1917) and other workers. 



And so Bordet once again suggests a physical basis for ana- 

 phylaxis. 



There, for the time being, the question must be left. 



And now, aftefi; very briefly sketching in some of the more 

 interesting phases of the problem of the mechanism of immunity, 

 surely we can, whilst admitting our inability to accept any one 

 general hypothesis, see something of a glimmering light, perhaps 

 cf the dawn, and we must at least pay a tribute to the genius of 

 Pasteur, Lister, Metchnikoff, Ehrlich, Bcrdet, great pioneers in 

 a research fraught with incalculable benefits to mankind and the 

 creatures over which man holds sway. 



