On Immunity with Special Reference to Cell Life, 



445 



The character of the specific union made it possible to find solutions 

 for a number of important questions. In the first place, regarding the 

 multiplicity of the hsemolysines, which occur normally in serum, it is 

 well known that numerous sera are able to dissolve blood corpuscles of 

 different species. For example, serum of the dog dissolves blood 

 corpuscles of the rabbit, guinea-pig, rat, goat, sheep, &c. The complex 

 nature of these haemolysines has been already indicated. 



Another question arises whether in a serum that is capable of such 

 manifold action there is present one single hsemolysine that destroys 

 different red blood-cells, or whether a whole series of hsemolysines 

 come into action, of which one is adapted to guinea-pig blood, another 

 to rabbit blood, &c. The solution of this question may be approached 

 in another way. The serum may be rendered inactive by heat, and 

 then placed in contact with red blood corpuscles of a given kind. 

 Then, supposing, for example, that rabbit blood has been employed, it 

 is found that if the fluid is freed from the erythrocytes by centrifugal- 

 isation and the " complement " afterwards added, it is no longer in a 

 position to dissolve rabbit blood, but has not suffered any impairment 

 of its action on other kinds. 



By this method of elective absorption it is proved that the normally 

 occurring haemolysines which chain the blood corpuscles of the rabbit 

 to themselves, are specifically adapted to this purpose. If with 

 suitable adjustment of conditions similar experiments be conducted 

 with other kinds of blood, results are obtained which force us to the 

 conviction that in such a serum acting on various kinds of blood 

 there are present absolutely different " intermediate bodies " (ana- 

 logues of the " immune bodies "), of which each one is specific for 

 one kind of blood, i.e., one is adapted for rabbit's blood, a second for 

 calf's blood, &c. Dr. Morgenroth and I have in some cases, indeed, 

 succeeded in proving that the " complements " which are adapted to fit 

 themselves to these "intermediate bodies," and occur in normal sera, 

 differ among themselves. If we reflect that in normal blood, in addi- 

 tion to these different haemolysines, there are besides a long series of 

 analogous bodies, agglutinines of very different kinds, bacteriolysines, 

 enzymes, anti-enzymes, we are brought more and more to the convic- 

 tion that the blood serum is the carriei' of substances innumerable as yet 

 little known or conceived of. 



Having obtained a precise conception of the method of action of 

 the lysines of the serum — of the haemolysines, and thereby also of the 

 bacteriolysines — it becomes possible for us to attempt to solve the 

 mystery of the origin of these bodies. I have in the beginning of 

 this lecture fully developed the " side-chain theory," according to which 

 the antitoxines are merely certain of the protoplasm " side-chains," 

 which have been produced in excess and pushed off into the blood. 

 The toxines, as secretion products of cells, are in all likelihood still 



