236 COLLECTED STUDIES IN IMMUNITY. 



by means of serum corresponding to the blood-cells employed has 

 very recently been employed by Buchner 1 exclusively as a reaction 

 for the presence of normal amboceptors. 



Although the principle advanced by Gruber as an invariable 

 means of differentiation has failed, we are far from identifying normal 

 and specific amboceptors. As already stated, we believe that in the 

 sense above described it has been proved that they vary. Here we 

 should like to emphasize that, despite individual multiplicity, all 

 amboceptors belong essentially to a common class of similarly react- 

 ing substances. 



To us these observations appear of interest also in another direc- 

 tion. Baumgarten 2 ascribes the haemolysis in a foreign serum 

 entirely to the influence of the amboceptors, which he identifies with 

 the agglutinins. He says that "while in themselves incapable of 

 effecting haemolysis, they put the red blood-cells into such a condition 

 that they allow their haemoglobin to escape even on relatively slight 

 osmotic disturbances." Just these slight osmotic disturbances, 

 according to Baumgarten, are caused by the foreign sera whose 

 osmotic tension is changed by heating (inactivation). Hence Baum- 

 garten regards the assumption of complements as entirely unnecessary. 

 In opposition to this we would like to call to mind the numerous 

 combinations described by us (even Bordet has described such for 

 the haemolysins obtained by immunization), in which the blood- 

 cells dissolve in their own serum,, i.e. in the ideal isotonic medium, 

 if they have previously been treated with an inactive serum (ambo- 

 ceptor) of a different species. Such cases clearly indicate that ha> 

 molysis by means of blood serum has nothing to do with isotonic 

 conditions; that it is rather due to a poisonous action which depends 

 on the coaction of two components amboceptor and complement. 



II. Concerning the Variability of the Complements. 



The plurality of the complements contained in a serum has been 

 proved by the most varied experiments. A separation of the indi- 

 vidual complements of the serum has been undertaken in various 

 sera by means of chemical or thermic influences, 3 by binding with 



1 Buchner, Berl. klin. Wochenschr. 1901, No. 33. 



2 Baumgarten, ibid., No. 50. 



3 Ehrlich and Morgenroth, see pages 11 et seq.; Ehrlich and Sachs, pages 

 195 et seq.; Wendelstadt, Centralblatt f. Bact. 1902, Vol. 31, No. 11. 



