242 COLLECTED STUDIES IN IMMUNITY. 



of the motion of flagella and cilia. The specific binding of the am- 

 boceptors is therefore not dependent, on a coarser or finer morpho- 

 logical structure : it can occur wherever the specifically related receptors 

 are present. 



For the doctrine of immunity these views constitute a new and 

 really concise definition of specificity. The latter thus loses the 

 systematic character originally given it by botany and zoology and 

 must from now on be regarded purely chemically, as absolutely 

 dependent on the conceptions as to the nature of the cell's receptors. 

 Every product of immunization is specific for those receptors by which 

 it was called forth, irrespective of where the receptors may be. 1 When 

 injected into an animal the receptor produces antibodies, and these 

 again, when they meet the receptor under suitable conditions, are 

 bound by the receptor. This binding, in our conception, always 

 remains specific. It matters not whether the receptor is peculiar 

 to the protoplasm of that species of cell which originally excited the 

 immunity, or whether it belongs to a different kind of cell of the 

 same species or to one of a strange species. 



Hence the principle of specificity of the amboceptors produced by immu- 

 nization is not violated when, for example, v. Dungern obtains hsemolytic 

 amboceptors by injections of ciliated epithelial debris, such as is contained in 

 goat milk. v. Dungern 2 has very properly pointed out this fact in emphasizing 

 the community of the receptors. The same holds true for the hsemolytic am- 

 boceptors obtained by Moxter 3 by injections of spermatozoa. Several different 

 zoological species, such as goat, sheep, and ox, possess a number of common 

 receptors in their blood-cells. 4 



On the basis of the side-chain theory as it has just been laid 

 down it is almost a matter of course that these receptors of the 

 protoplasm which excite the production of the amboceptors are 

 normally present dissolved in the body fluids, a physiological proto- 

 type of what occurs to such a high degree in consequence of immu- 

 nization. 5 



1 See the explanations by Ehrlich concerning the receptor apparatus of the 

 red blood-cells in Schlussbetrachtungen, Vol. VIII, of Nothnagels spezielle 

 Pathol. und Therapie, Vienna, 1901. 



2 v. Dungern, Munch, med. Wochenschr. 1S99, No. 38. 



3 Moxter, Deutsche med. Wochenschr. 1900, No. 1. 



4 Ehrlich and Morgenroth, page 88. 



6 It has already been shown that as a result of injection of amboceptors into 

 sensitive animals a considerable number of cell receptors are thrust off, which 



