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 

 hquid 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 Uters 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 fasces 

 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 



