450 ELEMOLYSINS AND ALLIED BODIES 



types of biogen receptors, all of them fitting the receptors of the 

 erythrocytes used for injection, but some of them also fitting the 

 receptors of other erythrocytes. Erythrocytes which do not 

 become hsemolysed when a certain immune serum is added to 

 them do not possess receptors capable of fitting any of the cyto- 

 philic groups of the amboceptors. We have seen, then, that the 

 cytophilic group of the amboceptors varies somewhat in structure. 



As stated above, there is reason to believe that the comple- 

 mento-philic group also varies ; for equal quantities of the same 

 erythrocytes, mixed with equal quantities of different normal sera, 

 require a very variable amount of the same amboceptors to induce 

 haemolysis. In this experiment, erythrocytes and amboceptors 

 are the same; they will unite equally in each case, so that any 

 difference in hsemolytic power must be due to a difference in the 

 union of complement and amboceptors. 



This complex nature of the amboceptors is of importance 

 clinically. In the treatment of certain bacterial diseases it 

 is customary to inject anti-serum derived from one animal only. 

 It may happen, however, that the amboceptors of this serum 

 do not possess complement o-philic groups which will fit the 

 complements of human blood. To increase the chance of there 

 being suitable complemento-philic groups, it would be desirable, 

 therefore, to use a mixed antitoxic serum, i.e. one containing 

 various amboceptors. Such a serum could be obtained by injecting 

 the same bacillus into various animals. 



As has been indicated above, the complement also is pro- 

 bably a compound body that is, there are various complements 

 normally present in the blood serum. The fact that the com- 

 plemento-philic group of the amboceptor is compounded so 

 that it can fit different complements would itself imply the 

 plurality of complements. This has been further proven by a 

 series of elaborate experiments by Ehrlich and Morgenroth and 

 others. (A summary of these experiments will be found in Hans 

 Sachs's article, Die Hcemolysine, pp. 58-63.) We will content 

 ourselves here with two of these experiments. I. If goat's serum 

 be warmed to 56 C., only a portion of the complements disappears 

 that is, the heated serum can still activate certain amboceptors. 

 The separation of these two fractions of complement in goats' 

 serum can also be effected by filtering the serum through a Pukall's 

 filter. By this latter method, two complement fractions could also 

 be demonstrated in horse's serum. II. Complement fractions behave 



