386 COLLECTED STUDIES IN IMMUNITY. 



as luxuries which are not in themselves of any significance for the 

 life of the organism. Of what use is it to a person or to an animal 

 to have circulating in his blood a great variety of substances 

 directed against heterogeneous materials which under normal cir- 

 cumstances never come into account, and which at the most are 

 brought into relation with these substances only by the experi- 

 menter? Of what use is it to a goat to have in its blood certain 

 substances which are directed against the red blood-cells or the 

 spermatozoa of other animals, since these do not normally get into 

 the circulation? Furthermore every experimenter finds that the 

 blood serum is subject to constant change in most of its haptins, a 

 fact which argues strongly against the assumption that all of these 

 substances in a free state play an important or even necessary role 

 in the organism. 



I cannot and do not deny that with such a superabundance of 

 combinations in every serum substances will also be present which 

 either by themselves or in conjunction with complements are able 

 to destroy invading injurious bodies, especially bacteria. These 

 substances then may be regarded as acting as defensive agents. In 

 spite of this, however, I believe it is wrong to group this most com- 

 plex system of haptins under the collective name alexin, because 

 this leads to an incorrect Unitarian view which cannot help scientific 

 progress. These remarks are in no way intended to detract from 

 the very valuable work of Buchner; his study on alexins, viewed 

 in the light of that time and according to the then state of science, 

 must be regarded as a masterpiece which has been of enormous value 

 in the development of this subject. 



Still another difference of opinion existing between Buchner 

 and myself concerns the bactericidal and hsemolytic power of nor- 

 mal blood serum, and these properties Buchner again ascribes to 

 the action of his alexin conceived as a simple substance. In oppo- 

 sition to this I have demonstrated that the conditions in normal 

 haemolysins are exactly the same as in the artificial hsemolysins, 

 for here again two different components act together: one of them 

 is thermostable while the other corresponds to the complements. 

 This fact has been confirmed by a large number of observers, among 

 whom I may mention v. Dungern, Moxter, London, P. Muller, Meltzer. 

 All these authors, like myself, have come to the conclusion that the 

 thermostable substance necessary for the lytic process corresponds 

 in every way to the artificially produced immune bodies or ambo- 



