308 INFECTION AND IMMUNITY 



1. Determination of tJie bacteriolytic power of serum against a 

 known microorganism in vivo:* 



A number of dilutions of the serum are made with sterile neutral 

 bouillon or salt solution, ranging from 1 in 20 to 1 in 500, or higher. 

 It is convenient to make a first solution of 1 in 20. One c.c. of 

 this mixed with 4 c.c. of broth will give 1 in 100. One c.c. of the 

 1 in 100 dilution with 1 c.c. of broth, 2 c.c. of broth and 4 c.c. of 

 broth will give 1 in 200, 1 in 300, and 1 in 500 respectively. Into 

 one cubic centimeter of each of these dilutions there is placed one 

 platinum loopful of a twenty-four-hour agar culture of the micro- 

 organism against which the serum is to be tested. Into another test 

 tube is placed 4 c.c. of broth, without serum, and with one loopful 

 of the microorganisms. The mixtures are thoroughly emulsified in 

 each case by rubbing the bacteria against the sides of the tube with 

 the platinum loop. 



Intraperitoneal injections into guinea-pigs are then made of 1 c.c. 

 of each of the serum-dilution-bacterial-emulsions. A control guinea- 

 pig (better two or three) receives 1 c.c. of the broth emulsion 

 one-fourth as many bacteria, therefore, as the animals receiving the 

 serum dilutions. 



Before making the injections, areas on the lateral abdominal 

 walls of the guinea-pigs are shaved, and small incisions made through 

 the skin, down to the muscular layers. The needle of the syringe 

 is then introduced perpendicular to the skin until it has penetrated 

 the peritoneum, and then carefully slanted to avoid puncturing the 

 gut, The animals need not be strapped down during this procedure 

 and afterward may be allowed to run about. 



After one-half hour, and again after one hour has elapsed, a drop 

 of peritoneal exudate is removed from each guinea-pig and examined 

 in the hanging drop for granulation and swelling of the bacteria. 

 The method of obtaining the peritoneal exudate is as follows : Small 



FIG. 39. CAPILLARY PIPETTE FOR REMOVAL OF EXUDATE IN DOING THE PFEIFFER 



TEST. 



glass tubing is drawn out into capillary pipettes, the ends of the 

 capillaries being again drawn to fine points in a small yellow flame. 



8 P. Th. Muller, "Technik d. serodiagnos. Methoden," Jena, 1909. 



