STUDIES ON H.EMOLYSINS. 79 



noted, exact investigation has shown * that these are due to the pres- 

 ence of one and the same receptor group in various elements. Thus 

 we have shown that the isolysins produced by injecting goats with 

 goat blood-cells act also on sheep blood-cells. We have further 

 shown that these sheep blood-cells possess certain kinds of receptors 

 which bind the goat lysin just as the receptors which are present in 

 the goat blood-cells do. We produced the strongest proof for this 

 community of receptors by means of crossed immunization, for we 

 succeeded in producing a typical isolysin by injecting goats with 

 sheep blood. 



Since all experiences, therefore, lead us to assume that each par- 

 ticular complex produces just the specific antibody, and since this 

 agrees exceedingly well with the assumption of a chemical union, 

 it would be a distinct backward step to adopt so vague a conception 

 as that of mechanical surface attraction. 



Were we to assume that the immune body enters the cell merely 

 mechanically, it would be necessary to drop the entire unity of the 

 immunization phenomena which follows from the side-chain theory. 

 It is probably quite generally conceded that the antitoxin acts on 

 the toxin in a purely chemical manner. Hence so far as dissolved 

 substances developed by the immunity reaction are concerned, the 

 chemical conception applies. Why then should this chemical action 

 suddenly cease w y hen the substances instead of being in solution are 

 present within the cell, and a new principle be assumed for this 

 case? This leads to the contradiction that in one case (when com- 

 bining with the erythrocytes) the immune body is bound, specifically 

 to be sure, but mechanically, while in the other case (when anchored 

 to an artificially produced anti-immune body in solution) it is bound 

 specifically but chemically. 



These considerations, and they could readily be greatly extended, 

 will suffice to show that the above-mentioned experiments are not 

 at all capable of shaking the side-chain theory, for by it alone is 

 a single uniform conception of the phenomena of immunity rendered 

 possible. 



II. Concerning Complementoids. 



The complements, which effect the activation of the normal 

 immune bodies and of those produced by immunization (amboceptors) 

 do not possess great theoretical or practical importance in the study 



1 See Third Communication, page 23. 



