VIII. STUDIES ON ILEMOLYSINS. 1 



SIXTH COMMUNICATION. 

 By Prof. Dr. P. EHRLICH and Dr. J. MORGENROTH. 



THE steady progress of the investigations in immunity is rendered 

 extremely difficult by the fact that in the immunization with living 

 cells and in the study of the immune sera thus obtained a large number 

 of different substances which exist simultaneously is concerned. 

 In our second communication we pointed out that the hsemolysins 

 present in normal serum, which act on different species of blood, are 

 not a single substance in the sense of Buchner's alexin; and in our 

 fourth communication we showed that this could be demonstrated 

 experimentally by means of elective absorption. It is possible that 

 just as many interbodies come into action as the varieties of blood 

 affected. We have also been unable to accept Bordet's Unitarian 

 view of the complements. On the contrary, as a result of our own 

 experiments we have become convinced that a large number of com- 

 plements exist together in blood serum. In like manner Bordet's 

 absorption experiments indicate a plurality of the bacterial agglutinins 

 and those of Malkoff a plurality of the normal hsemagglutinins. 

 The results of these experiments have been gathered together by M. 

 Neisser 2 in a study in which, on the basis of the same principles, he 

 demonstrates the variety of the antitoxic antibodies occurring in nor- 

 mal serum. In conformity to this, the reactive antibodies produced by 

 injections of serum of foreign species are most varied in their nature, 

 and we are only just beginning to gain an insight into their constitution. 

 Aside from the numerous coagulins and antiferments thus produced, 

 it is of the utmost importance, so far as the discussion of immunity 

 problems is concerned, to recognize the fact that the complements 



1 Reprinted from the Berliner klin. Wochenschr., 1901, Nos. 21 and 22. 



2 Deutsche med. Wochenschr., 1900, No. 49. 



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