THE PHENOMENON OF AGGLUTINATION 



233 



trated by the two following protocols, also taken from Castellani's 

 paper: ' 



Note: All of these protocols are taken from Castellani's communication, loc. cit. 



These facts, variously confirmed, tend to corroborate the concep- 

 tion of the production of major and minor agglutinins outlined 

 above. 



It is of practical and theoretical importance to mention that 

 complete absorption of specific agglutinin by a single exposure to 

 homologous bacteria, however thickly emulsified, is not possible. It 

 is always necessary to absorb repeatedly, and even then a minute 

 trace of agglutinin may eventually remain. Eisenberg and 

 Yolk, 44 , 45 who have studied these conditions particularly, attribute 

 this to the nature of the union of agglutinogen with agglutinin, 

 which they conceive as following the laws of mass action this ac- 

 counting for the persistence of a small "rest" of free agglutinin, 

 even after repeated absorption by partial dissociation. The prin- 

 ciple involved here is identical with that discussed in connection with 

 antigen-antibody union in general. 



It is not only in the sera of immunized animals, however, that 

 agglutinins are found. Just as the other antibodies, antitoxins, and 

 bactericidal sensitizers may be found in the blood of normal animals, 

 so agglutinins for various bacteria may be normally present. These 

 normal agglutinins do not in any respect, further than that of quan- 

 tity, differ from the immune agglutinins and follow the same laws 

 of specificity which have been described for the latter. It has been 

 shown a number of times that such normal agglutinins are not pres- 



44 Eisenberg and Volk. Zeitschr. f. Hyg., Vol. 40, 1902. 



45 Eisenberg. Centralbl f. Bakt., Vol. 34, 1903. 



