AGGLUTININS AND PRECIPITINS 



81 



combination of these, using first the subcutaneous or intraperitoneal 

 routes followed later by intravenous injections. Bacteria are usu- 

 ally killed by heat or chemicals before injection, although after im- 

 munization is well under way living organisms may be employed. 

 The use of living organisms is often of service in the development 

 of a serum of high titer. 



POUPACTd U a. 



PIG. 5. Method of complete bleeding from the femoral vessels of the rabbit (see 

 text page 83). 



The following will serve as a fairly typical example of the process of 

 immunization for the production of an anti-typhoid agglutinin. The cultures 

 used are twenty-four hour agar slants inoculated by zig-zagging the loop 

 back and forth over the surface so as to have the surface well covered by 

 growth. A measured amount, 5.0 c.c. or 10.0 c.c. of sterile salt solution is 

 added, the tube allowed to stand ten or fifteen minutes and then vigorously 

 rotated between the palms of the hands. This procedure gives a much 

 smoother emulsion than washing off by sucking in and blowing out from a 

 pipette or by scraping off with a platinum loop and is less susceptible to 

 6 



