XX. DIFFERENTIATING COMPLEMENTS BY MEANS OF 

 A PARTIAL ANTICOMPLEMENT. 1 



By H. T. MARSHALL, Fellow of the Rockefeller Institute, and Dr. J. MORGEN- 

 ROTH, Member of the Frankfurt Institute. 



THE question whether the serum of one and the same species 

 contains a plurality of complements or only a single one seems to 

 us to have been positively decided in favor of the pluralistic concep- 

 tion. This decision has been brought about mainly by the observa- 

 tions of Ehrlich and Morgenroth, 2 of Wassermann, 3 Wechsberg, 4 

 Wendelstadt, 5 and by the recently published studies of Ehrlich and 

 Sachs. 6 Nevertheless, we shall briefly describe an experiment which, 

 in a single instance at least, constitutes a proof for the plurality of 

 the complements. Our object in doing this is not that the number 

 of arguments may be further increased, for they are already amply 

 sufficient, but that we may call attention to a method of demonstra- 

 tion which has not heretofore been employed. 



Because of purely technical difficulties the most rational and 

 simplest method of differentiation, namely, by means of anticomple- 

 ments, has not thus far been employed in this question. As is w T ell 

 known, it is very easy by immunizing with serum containing com- 

 plement or complementoid to obtain potent anticomplements. Such 

 anticomplement sera, however, usually contain anticomplements cor- 

 responding to the sum of all the complements originally injected, 7 

 and are, therefore, not adapted to the separation of complements. 



1 Reprinted from the Centralblatt f. Bact. Original Vol. XXXI, No. 12, 

 1902. 



2 See pages 1 1 , 56, 86. 



3 Wassermann, Zeitschr. f. Hyg., Vol. XXXVII, 1901. 



4 Wechsberg, Sitzung d. k. k. Ges. d. Aerzte in Wien, Wiener klin. Wochen- 

 schr. 1901, No. 48. 



6 Wendelstadt, Centralblatt f. Bact. Part I, Vol. XXXI, No. 10. 

 8 See page 195 et seq. 

 ' See page 63 et seq. 



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