Isoagglutinim and Agglutinoids 49 



bacilli in some part of the body. Although anti-typhoid sera, to confine myself 

 to these, usually show marked agglutinating power for these germs, when potent, 

 it has at times been observed that such sera were strongly protective and but 

 slightly agglutinative. It has been claimed that .such agglutinin.s may be ac- 

 cepted as an index of immunity, but this .seems scarcely justified in view of the 

 fact that strongly agglutinative sera have been obtained from persons dying from 

 typhoid fever. Van Emden (1899, p. 31) has made a similar observation upon 

 rabbits dying of infection with B. aerogenes. I am inclined to believe that the 

 agglutinins represent but a group of the many antibodies with which the 

 organism reacts to infection or the like, that they are immune substances directed 

 against some of many injurious factors. It follows from what we know of the 

 individual differences which exist in animals that the reaction may take place 

 more along some lines than upon others, and this would explain the presence of 

 an excess of one immune substance, another, perhaps more vital one, being deficient. 

 The use to the economy of the agglutinin.s under normal and pathological conditions 

 is certainly obscure as yet. 



The occurrence of Isoagglutinins together with isolysins in human 

 blood in disease has already been referred to on p. 42. 



The existence of Agglutinoids, analogous to toxoids and precipitoids, 

 is indicated by the observations of Eisenberg and Volk (6, VIII. 1902), 

 there being apparently a stable combining group, and a labile precipi- 

 tating group, in agglutinating sera. They found inactivated, as also old 

 antisera, to retard the action of fresh antiserum. Bail (Arch. f. Hyg. 

 1902, cited by Kraus and Pirquet) also believes in the existence of two 

 groups in such antisera. (Compare with precipitins.) 



Antiagglutinins have been obtained through the treatment of animals 

 with haemagglutinins. Venom-agglutinins may be neutralized by anti- 

 venene (Kanthack), ricin-agglutinins by anti-ricin serum (Ehrlich). Ford 

 (3, VII. 1902, p. 367), taking either the normal agglutinin of rabbits, or 

 the artificial agglutinin developed in rabbits through fowl-blood injection, 

 injected it into fowls, and obtained antiagglutinin. It seems however 

 premature for him to conclude that the immune-agglutinins are only 

 quantitatively different from normal agglutinins. He states that 

 Wassermann has been unable to obtain an antiagglutinin for the 

 agglutinin of B. pyocyaneus (formed in pyocyaneus-treated goats), and 

 that Kraus and Eisenberg had been equally unsuccessful in obtaining 

 bacterial antiagglutinins. 



Differences between Agglutinins and Precipitins, etc. 



Tchistovitch (v, 1899, p. 418) has already drawn attention to the 

 fact that precipitins are distinct from agglutinins, on the ground that 



N. 4 



