INFECTION AND RESISTANCE 



The agglutinogen, or agglutinin-inducing substance in the bac- 

 teria is apparently an inherent part of the bacterial protein, and 

 agglutinins may be produced in animals by injection not only of 

 living and dead whole bacteria, but by bacterial extracts, prepared 

 in various ways. And, furthermore, just as the agglutinins of serum 

 are absorbed out of a serum by the whole bacteria, they may be neu- 

 tralized by the dissolved bacterial extracts. 



Just what the nature of the agglutinogen is has been a matter 

 of prolonged controversy, Pick 16 and others claiming that it is pos- 

 sible to obtain an agglutinogen by alcohol precipitation from old 

 bacterial cultures which, upon further purification, can be found to 

 give none of the usual protein reactions (Biuret, Millon). It is by 

 no means certain, however, that Pick's results are correct. In fact, 

 many objections have been advanced against them, and the accept- 

 ance of an antigen of non-protein nature is so opposed to all our 

 knowledge regarding antigens in other cases that Pick's results 

 should not be taken as final until very careful revision of the experi- 

 mental facts has been carried out. That the agglutinogen is, to a 

 certain extent, subject to dialysis has been claimed because of ex^ 

 periments in which specific agglutinins have appeared in the sera of 

 animals into whose peritoneal cavities celloidin sacs, filled with bac- 

 teria, have been placed. 17 



There has been a great deal of discussion regarding the possible 

 localization of the agglutinogen of bacteria in the ectoplasmic layers 

 of the cells, and especially in the flagellar substance. We have seen 

 that, as a matter of fact, nonmotile bacteria are subject .to the phe- 

 nomena of agglutination just as are the motile forms, but numerous 

 attempts were made during the earlier stages of our knowledge of 

 this reaction to demonstrate that changes in ectoplasm and flagella 

 accompanied the actual agglutination. Gruber 18 himself held the 

 opinion for a time that the clumping was due to an eotoplasmic 

 swelling which rendered the bacteria sticky, causing them to hold 

 together after chance approximation. He soon gave up this idea 

 himself, but a similar theory was for some time upheld by ISTicolle 19 

 and others. 



Malvoz 20 in 1897 devised an ingenious method by which he be- 

 lieved that he could show that the agglutination of bacteria depended! 

 upon their ectoplasmic substances. He passed the typhoid emulsion 

 through Chamberland filters and, when the bacilli had been caught 



16 Pick. "Hof meister's Beitrage," 1901, 1902. 



17 This would be in keeping with Pick's work just referred to, and should 

 be subjected to the same criticism before final acceptance. For a more de- 

 tailed discussion of these conditions the reader is referred to the article by 

 Paltauf, "Kolle u. Wassermann Handbuch," Vol. 4, part 1. 



18 Gruber. Munch, med. Woch., 1896. 



19 Nicolle. Ann. de I'Inst. Past., 1898. 



20 Malvoz. Ann. de I'Inst. Past., Vol. 11, 1897. 



