178 



A MANUAL OF BACTERIOLOGY 



scopical examination of hanging-drop specimens of the organism 

 suspended in a drop of the immune serum to which a trace of fresh 

 peritoneal fluid (complement) is added. If the organism is homolo- 

 gous with the immune serum, the bacteria are soon transformed 

 into granules. Controls are put up at the same time with a known 

 strain of the organism with (1 ) its homologous immune serum -f- com- 

 plement ; (2) non-immune serum 

 of the same animal -f- comple- 

 ment ; also of the organism being 

 tested with non-immune serum of 

 the same animal -j- complement. 

 The peritoneal fluid may be ob- 

 tained by injecting 3-4 c.c. of 

 broth into the peritoneal fluid 

 of a guinea-pig and four hours 

 later withdrawing the fluid (now 

 turbid with leucocytes) and oen- 

 trifuging, or allowing it to 

 stand on ice for twenty-four 

 hours. 



In the second, or indirect, 

 method, the organism is used to 

 prepare an immune serum by 

 injecting an animal (e.g. a rabbit) 

 with it, and the immune serum 

 so prepared is tested on a known 

 virulent stain in the peritoneal 



cavity of guinea-pigs in order to ascertain whether or no it brings 

 about bacteriolysis, i.e. the Pfeiffer phenomenon. 



Deflection, deviation, 1 diversion or blocking of complement. 

 Pfeiffer in 1895 observed that a large amount of immune serum 

 might not protect an animal from the cholera vibrio, while a smaller 

 amount with the same dose of vibrio did so. In 1901 Neisser and 

 Wechsberg demonstrated an analogous reaction in vitro. They 

 studied the effect of a bacteriolytic immune serum when varying 

 amounts of the inactivated serum were employed. The quantity 

 ranged from 0-0005 c.c. to 1 c.c. To each of these amounts constant 

 volumes of normal serum and bacterial suspension were added. No 

 bacteriolysis occurred when large and small amounts of immune 

 serum were used, but with medium amounts bacteriolysis was 

 complete. Theyj^explained this anomalous reaction, the absence 



1 " Fixation of complement " (p. 183) is frequently erroneously 

 termed " deviation of complement." 



FIG. 34. Diagram to represent 

 the condition of the blood in 

 which there is an excess of 

 amboceptors. The ambocep- 

 tors (white) unite with both 

 complement (black) and re- 

 ceptors (dotted), so that the 

 receptors cannot combine with 

 the amboceptor-complement 

 groups. 



