VI 



Curve No. 11 



2 cc. 24h B. typhos. cul- 

 ture introduced intrape- 

 ritoneally. No aggluti- 

 nin curve occurred. But 

 27 days later, when the 

 amount of agglutinin 

 had decreased to 400, the 

 corresponding dose of 

 culture produced a typi- 

 cal curve with a maxi- 

 mum of 1429. 



After these observa- 

 tions it seemed of in- 

 terest to try if the dif- 

 ference between the ac- 

 tively and passively 

 immunised organism 

 should depend upon 

 the circumstance, that 

 the agglutinin in the 

 two cases was not quite 

 identical. It seems that 

 the typhoid and cholera 

 agglutinins (or perhaps 

 rather the antibodies) 

 might possibly possess 

 quite another "neutra- 

 lising' action upon the 

 microbes in the pas- 

 sively immunised orga- 

 nism and in vitro than 

 in an actively immuni- 

 sed animal. 



A number of experi- 



