On Immunity with Sj^ecial Reference to Cell Life. 429 



toxic action. From the constancy of the combining capacity, and the 

 diminution in the toxicity, it was to be inferred that the toxophore group 

 was ver}' unstable, but the haptophore group more stable, and also that 

 the deterioration of the toxophore group proceeded of necessity quite 

 independently of any relation to the haptophore group. 



If we now designated a toxine molecule, of which the toxophore 

 group is destroyed, but its haptophore group retained, as " toxoid," 

 then the above-described process will represent the quantitative pro- 

 gress of the conversion of the toxine molecules into toxoid molecules. 

 Such a toxoid molecule has the same quantitative combining affinity . 

 for antitoxine as the original toxine molecule, in spite of the disappear- 

 ance of toxicity to the animal body. In other words, the affinity of 

 the haptophore group for the antitoxine is absolutely independent of 

 the existence of a toxophore group. Also, in the original toxine mole- 

 cule, both groups must be to such a degree non-related or independent 

 of one another, that a mutual reaction between them does not take 

 place. This conception of the constitution of diphtheria toxine, after 

 more extensive, very exact, and much varied experimentation, based 

 on its partial neutralisation by antitoxine, has been confirmed in the com- 

 pletest manner possible. At this time it would be superfluous for me 

 to enter into all the details pertaining to these investigations. It need 

 only be remarked that in principle the same relations have been 

 established for tetanolysine by Madsen, for snake-poison l)y Meyers, 

 and for the milk-curdling ferment by Morgenroth. 



The separation of the characteristic atom groups of the toxine mole- 

 cule into a haptophore and a toxophore group, afforded not merely a 

 satisfactory chemical explanation of the process of neutralisation : the 

 possession of the knowledge of the existence of these groups yielded us, 

 at the same time, the key to the nature of the toxic property of 

 toxines, and to the mystery of the origin of the antitoxines them- 

 selves. After it had been established by the already described method, 

 that the toxine molecule was possessed of a definite haptophore group, 

 which accounted for its capacity to enter into combination with other 

 bodies, it was immediately necessary to inquire into the question 

 whether, and if so to what degree, this group entered into the causa- 

 tion of the sym^ptoms of illness. That chemical substances are only 

 able to exercise an action on the tissue elements with which they are 

 able to establish an intimate chemical relationship is a conception of a 

 general nature, which has been entertained since the birth of scientific 

 medicine. 



It is astonishing, almost astounding, that this axiom, of which the 

 theoretical importance has been so long recognised, and which has 

 served indeed as the first ground for certain therapeutical procedures, 

 should as a matter of fact have played in the building up and furtherance 

 of scientific pharmacology a rule so insignificant in proportion to its great 



