134 Immunity 



the experiments. Thus, with typhoid bloods, the agglutination of the 

 typhoid bacillus usually occurs within an hour in dilutions of i : 50, 

 but the agglutinability of the culture employed should be known before 

 the experiment is undertaken. 



Similarly, when the method is employed for the differential determi- 

 nation of bacteria, the value of the serum should be known at least 

 approximately. 



The agglutinins when injected into animals effect definite 

 chemico-physiological reactions with the formation of anti- 

 bodies inhibiting their own activity. 



III. The Antitoxins. In the synopsis of immunity ex- 

 periments already given the history of the discovery and 

 development of the anti-bodies has been outlined, together 

 with references to the original contributions in which they 

 were made public. 



In the section upon the "Explanation of Immunity" we 

 have seen that the best mode of accounting for the occur- 

 rence of antitoxins is afforded by Ehrlich in the lateral-chain 

 theory. He regards them as cell haptophores receptors 

 that are found in excess of the requirements, by cells fre- 

 quently stimulated by the presence of bacteria-products 

 possessing adapted haptophores. The receptors are under 

 normal conditions engaged in maintaining the proper nutri- 

 tion of the cell; under abnormal conditions (as when pre- 

 empted by the inert or injurious haptophores of the bacterio- 

 products) are obliged to increase in number to compensate 

 for the damage done the cell. The substances by which 

 anti-body formation can be stimulated must bear a resem- 

 blance to the normal nutrient substances absorbed by the 

 cells in that they are provided with haptophore groups 

 corresponding with the haptophore groups of the cells and 

 so adapted for union with them. Mineral substances and 

 alkaloidal substances have no such adaptations, but bacte- 

 rial products, the toxalbumins of various higher plants, 

 venoms, enzymes, and other proteid combinations have. 

 The possession of the haptophore groups determines whether 

 or not the cell can stimulate anti-body formation, and the 

 ability to produce anti-bodies shows the existence of the 

 haptophore groups. 



The attachment of the haptophore groups to the cells is 

 usually shown by morbid action of the cells in cases where 

 there are associated toxophore groups, as in the case of the 

 bacterio-toxins, but may not be discovered if there are no 

 toxophore groups. The combination of the toxin-hap- 



