ENDOTOXIN OF WHOOPING-COUGH BACILLUS. 491 



salt in a dry condition, and to add distilled water just before using 

 them. In this way the poison may be kept for some time, although 

 we have noted that even when kept from moisture it slowly loses 

 its power. 



The serum that we formerly obtained by injecting animals with 

 living cultures has no power to neutralize the endo toxin. We are 

 now engaged in an attempt to obtain an antitoxic serum by in- 

 jecting endotoxin instead of bacteria. 



