ISOLATION OF SPECIFIC PATHOGENES 83 



typhoid serum, the action may by no means be abso- 

 lutely specific. 



Schepilewski (Schepilewski, 1903) and Altschuler 

 (Altschuler, 1903) have also used agglutination as a 

 means of precipitating the bacteria after enrichment 

 cultivation in broth. The former incubated the cul- 

 ture at 37 for 24 [hours, then added a serum of 

 high potency, allowed the mixture to stand for 2 

 to 3 hours, and then centrifuged. The supernatant 

 liquid was removed, and the mass of agglutinated cells 

 broken up by shaking with glass beads and salt solu- 

 tion. Upon plating upon litmus lactose agar the organ- 

 isms could be detected. In this way positive isolation 

 was made from water containing i loopful of a broth 

 culture in 50 liters of water. Altschuler's method of 

 enrichment was essentially like that of Schepilewski. 

 From the surface of the culture developed at 37, 

 10 c.c. were removed to a tapering tube provided with a 

 rubber tube at the bottom. Serum was added in the 

 proportion of one part in 50, the culture agitated to 

 release entangled non-agglutinated bacilli and the 

 sediment run into a tube containing i per cent peptone 

 and 0.5 per cent salt. The agglutinated mass was broken 

 up by shaking with sand, and the culture incubated at 

 37 for 24 hours, then plated on Drigalski-Conradi 

 plates. The organism was isolated from dilute suspen- 

 sions in water (150 in i liter) and also from the faeces 

 of a typhoid patient from which other methods gave 

 negative results. 



Precipitation Methods. A number of methods for 

 concentrating typhoid bacilli in water by chemical 



