THE PHENOMENON OF AGGLUTINATION 225 



upon the filters, he subjected them to prolonged washing. The ba- 

 cilli, now removed from the filter by passing fluid through in the 

 opposite direction, were no longer motile or agglutinable either 

 by formalin, safranin, or other chemical agents, nor by agglutinating 

 sera. Dineur, 21 repeating the experiments of Malvoz, came to the 

 same conclusions. He decided that in agglutination the bacteria 

 became entangled with each other by means of the flagella. Harri- 

 son, 22 in later studies working under Tavel, attempted to dissolve 

 out the ectoplasmic layers of bacteria with pyocyanase, and from his 

 experiments also came to the conclusion that the agglutinogen was 

 contained in the external layers. Similar results were obtained by De 

 Eossi. 23 



Further studies on the same problem are those of Smith and 

 Reagh. 24 These investigators worked with two strains of bacilli, 

 both of which they regarded as belonging to the hog-cholera group, 

 though the one was motile and the other nonmotile. When rabbits 

 were immunized with the nonmotile bacillus an agglutinin was ob- 

 tained which acted upon this bacillus differently and less powerfully 

 than did the agglutinin produced with the motile one. Contact witK 

 the nonmotile bacillus did not deprive the serum produced with the 

 flagellated organism of the agglutinins for the latter. They con- 

 clude that two agglutinins were involved one incited by the ecto- 

 plasm and flagellar substance, the other by the bacterial cell body 

 proper. Rehns as well as Paltauf have criticized these results by 

 questioning the species identity, of the two bacilli employed in the 

 experiments, referring the phenomenon to the occurrence of group 

 agglutination. 



As a matter of fact our present knowledge of agglutination no 

 longer justifies the association of agglutination with flagella,/ !N"on- 

 motile as well as motile bacteria are readily agglutinated, and we 

 have much evidence which will be discussed presently which shows 

 that the agglutination reaction is governed by many of the laws 

 which obtain in colloidal flocculations.^ This, however, does not ex- 

 clude the possibility that it is the ectoplasmic zone chiefly which 

 takes part in the reaction.. Furthermore, loss of motility, which 

 always accompanies agglutination when a motile organism is under 

 observation, is an extremely valuable aid in guiding us in our judg- 

 ment of incomplete reactions.. 



That changes may be brought about in bacterial agglutinogen by 

 various methods of treatment has been shown by a number of work- 



21 Dineur. Bull, tie I'Acad. de Med. de Beige, 1898, cited from Smith and 

 Beagh. 



22 Harrison. Centralbl. f. Bakt., Vol. 30, I, Orig. 1901. 



23 De Rossi. Centralbl. f. Bakt., I,Vols. 36 and 40. 



24 Smith and Reagh. Journ. of Med. Ees., Vol. 10, 1903. 



