ON SPECIFIC THERAPEUTICS. 5 



to be followed, the study of the laws which govern 

 distribution is exceedingly difficult. Besides, 

 owing to the great number of chemicals at our 

 disposal, a large amount of empirical work must 

 be carried out before we are able to find those 

 substances which in any given case will give the 

 desired mode of distribution. All the greater, 

 then, must be our admiration for the powers of 

 nature, in view of the fact that the living 

 organism, when it takes upon itself the pro- 

 duction of curative agents, does this in such a 

 manner as to form ideal aetiological remedies. 

 The protective substances of the blood, with 

 which this lecture is concerned, completely fulfil 

 the requirements of the case, and the study of 

 antigens and antibodies may form the basis of the 

 relationships which must exist between con- 

 stitution, distribution, and action, in order that 

 our treatment may be successful. 



Since the conditions of substances treated of 

 in the study of immunity are specially clear and 

 matters of common knowledge, I shall begin the 

 discussion of my views regarding distribution 

 and localisation with the consideration of this 

 class of phenomena of pharmaco-dynamic and 

 toxicological action. 



The discovery of antitoxins by von Behring, 



