210 Professor Svcmte. Arrlmiius [JniK 



WEEKLY EVENING MEETING, 

 Friday, June 9, 1911. 



His Grace The Duke of Northumberland, K.G. P.O. D.C.L. 

 LL.D. F.E.S., President, in the Chair. 



Professor Svante Arrhenius, D.Sc. Hon.F.Pt.S. 



Hon.F.C.S. Hon.M.R.I., 



Director, Nobel Institute of Physical Chemistry. 



AppUcafioJis of Physical Chemistry to the Doctrine of Immunity. 

 Antigenes and Antibodies. 



I. — Introduction. 



The doctrine of antigenes and antibodies is of very recent date. 

 The first systematic investigations in this field, which has developed 

 so rapidly and become of enormous importance, are due to Behring 

 and Kitasato (1890). It is quite natural that attempts should be made 

 to systematize and explain the vast material collected, in order that 

 there should be a general survey of the field of work. The most 

 prominent fact is that it is generally possible, by injection of dif- 

 ferent substances of organic origin into the veins of an animal, to 

 obtain from the blood of that animal a serum which neutralizes 

 the action of the injected substance. This is called " antigene " ; 

 the active neutralizing body in the blood-serum is called " antibody." 



It seems rather natural to compare this neutralization between 

 antigene and antibody with the very familiar neutralization process 

 occurring on mixing an acid with a base. This idea was at first de- 

 veloped by Ehrlich, who was prevented by the great difficulties he 

 encountered from carrying out his conceptions. These difficulties are 

 largely dependent upon the slowness of the reaction of these substances, 

 with the incompleteness of their reactions, and with the instability of 

 the reagents. A great number of investigations regarding these 

 phenomena have been made by Madsen in Copenhagen, and by 

 myself. I will now try to describe the more general features of the 

 results of these and similar studies. 



Many of the antibodies are obtained by the injection of red 

 blood-corpuscles into the veins of animals. Some of these anti- 

 bodies possess the property of causing hemolysis — i.e. red blood- 

 corpuscles of the same kind as the injected ones, under the in- 

 fluence of these antibodies, give up their red colouring matter, the 



