272 RECEPTORS OF THE THIRD ORDER 



the combining group of any given antigen that acts as the 

 cell stimulus. Hence we may have an " anticytophil ambo- 

 ceptor" or an " anticomplementophil amboceptor." These 

 antiamboceptors and the anticomplements are analogous to 

 antitoxin, antiagglutinin, etc., and hence are receptors of 

 the first order. 



ANTISNAKE VENOMS. 



A practical use of antiamboceptors is in antisnake venoms. 

 Snake poisons appear to contain only amboceptors for differ- 

 ent cells of the body. In the most deadly the amboceptor is 

 specific for nerve cells (cobra) , in others for red corpuscles, 

 or for endothelial cells of the bloodvessels (rattlesnake). 

 The complement is furnished by the blood of the individual 

 bitten, that is, in a sense the individual poisons himself, 

 since he furnishes the destroying element. The antisera 

 contain antiamboceptors which unite with the amboceptor 

 introduced and prevent it joining to cells and thus binding 

 the complement to the cells and destroying them. With 

 this exception these antibodies are chiefly of theoretical 

 interest. 



FAILURE OF CYTOLYTIC SERUMS. 



The discovery of the possibility of producing a strongly 

 bactericidal serum in the manner above described aroused 

 the hope that such sera would prove of great value in passive 

 immunization and serum treatment of bacterial diseases. 

 Unfortunately such expectations have not been realized and 

 no serum of this character of much practical importance 

 has been developed as yet (with the possible exception of 

 Flexner's antimeningococcus serum in human practice. 

 What hog cholera serum is remains to be discovered). 



The reasons for the failure of such sera are not entirely 

 clear. The following are some that have been offered: (1) 

 Amboceptors do not appear to be present in ver.y large 

 amount so that relatively large injections of blood are neces- 

 sary, which is not without risk in itself. (2) Since the com- 

 plement is furnished by the blood of the animal to be treated, 

 there may not be enough of this unite with a sufficient 



