72 MECHANISM OF AGGLUTINATION. 



that the agglutinable substance existed " entirely in the outer 

 layers of the bacilli." 



Jochmann,'^' in abstracting a paper by Kohler, remarked that 

 Harrison had in a very clear manner proved Nicolle's assumption 

 that the agglutinable substance is found in the outer membranes 

 of the bacteria. With this I do not agree. The function of a 

 cell membrane is to retain the cell contents, and the membrane of 

 the typhoid bacterium retains the agglutinable substance to a 

 considerable extent. That it slowly diffuses through is admitted 

 from the scanty formation of Kraus' precipitate in younger 

 cultures, and the more copious precipitation in older cultures. 

 But if we remove the capsule or membrane there is no restraint 

 put upon the diffusion of the agglutinable substance from within 

 the cell. Harrison's experiments simply show that by removing 

 the membrane or capsule one of the slowly diffusible constituents 

 of the cell can be quickly removed, a circumstance which no one 

 would have doubted. They do not prove that the agglutinable 

 substance is in the surface layers of the cell. One might remove 

 the covering from a bee-hive, and with the same amount of reason 

 say that the bees which swarm out were in the covering, or when 

 an egg is broken that all the fluid contents were originally in the 

 substance of the shell. No ! The agglutinable substance saturates 

 the bacterium as a whole ; there is no evidence to show that it is 

 otherwise. 



Jochmann, Cent. f. Bakt. 1 Abt. xxx. 585. 



