THEORIES OF AGGLUTINATION 189 



diseases, e.g. pneumonia, chromocyte clumping may be a 

 marked feature. 



Various theories have been propounded to account for 

 the phenomena of agglutination : 



1. Pfeiffer and Emmerich and Loew regarded agglutina- 

 tion as a vital paralysis of the bacilli due to the action of a 

 bacteriolytic enzyme. Agglutination, however, is not a 

 vital phenomenon, for dead bacilli agglutinate, and bac- 

 teriolytic enzymes seem to be destroyed by temperatures 

 at which agglutinins remain unaffected. 



2. Gruber, Dineur, and Nicolle supposed that a glutinous 

 substance, " glabrificin," is absorbed from the serum by 

 the bacilli causing the cell membranes or the flagella to 

 become adhesive ; but this explanation will hardly account 

 for the aggregation of non- motile organisms. 



3. Paltauf and Duclaux considered that a precipitate 

 is produced in the medium, which during flocculation 

 mechanically carries the bacilli with it ; but there is no 

 demonstrable evidence that such precipitation occurs. 



4. Bordet separated the mechanism of agglutination 

 into two stages (1) fixation of agglutinin, and (2) aggre- 

 gation. The fixation of agglutinin by the organisms he 

 considers to be analogous to the adsorption of a dye by a 

 tissue ; and once the agglutinin is fixed, the organisms 

 obey the laws of inert particles, aggregation being caused 

 by changes in surface tension, in the molecular attraction, 

 between the organisms and the surrounding medium, a 

 view supported by Craw. 1 Ohno, 2 however, believes 

 that the union of agglutinin and agglutinable substance 

 is not analogous to the fixation of a dye by a tissue, but 

 that it is a chemical combination, as maintained by Ehrlich. 



Agglutinated bacteria are not injured by agglutination ; 



1 Journ. of Hygiene, vol. v, 1905, p. 113. See also Joos, Zeitschr. f. 

 Hyg., xxxvi, p. 422, and ibid, xl, p. 203. 



2 Philippine Journ. of Science, vol. iii, 1908, p. 47. 



