146 THE PRINCIPLES OF IMMUNOLOGY 



PFEIFFER PHENOMENON (Continued) 



Weight of Dose of Dose of 



guinea-pig spirilla immune Examination of 



in grams in grams serum in c.c. Result peritoneal fluid 



230 0.002 0.0005 Died during After 25 minutes, a few 



night granules, numerous active 



spirilla. Progressive in- 

 crease of spirilla. 



200 0.002 0.2 c.c. Died during After 25 minutes, few gran- 



normal night ules, numerous active 



guinea-pig spirilla. Autopsy after 



serum as several hours snowed pus 



control on the liver, numerous 



spirilla mostly free in exu- 

 date, with granules both 

 free and within cells. 



In the foregoing experiment it is seen that 0.003 c.c. immune serum 

 serves to protect a guinea-pig of about 200 grams from an otherwise 

 fatal dose of cholera spirilla. Pfeiffer used this method to titrate bac- 

 teriolytic sera and in this case would have indicated the serum as 

 containing in each cubic centimeter 333 immune units. 



Bacteriolysis in Vitro. Further study of the phenomenon more 

 particularly by Metchnikoff and by Bordet led to the discovery that the 

 process may be demonstrated in vitro, in spite of Pf eiffer's failure to do 

 so. Metchnikoff was able to produce lysis of spirilla in hanging drop 

 preparations by adding to the mixture of spirilla and immune serum an 

 extract of leucocytes, thus offering evidence in favor of the influence 

 of leucocytes in destruction of bacteria. Bordet demonstrated that 

 although the activity of the immune serum is destroyed by heat of 

 50 C. to 60 C., the serum may be rendered active again by the addi- 

 tion of a small amount of fresh serum, an amount of fresh serum in 

 itself incapable of producing bacteriolysis. He found that the speci- 

 ficity of the immune serum resides in a substance which he later named 

 the sensitizer (the Ehrlich amboceptor). The alexin of Buchner 

 (complement) was found to exhibit no specificity and was not increased 

 by immunization. In the course of these studies Bordet found that 

 the corpuscles in the fresh normal guinea-pig serum were agglutinated 

 by the immune goat serum and that the spirilla were often likewise 

 agglutinated. Suspecting that if both blood-cells and bacteria are 

 agglutinable, the blood-cells might be the subjects of lysis as well as 

 are bacteria, Bordet was led to the discovery of the- phenomenon of 

 hemolysis. The studies of Toitsu, Matsunami and Kolmer would indi- 

 cate that all bacteriolysis is not necessarily dependent upon the activity 

 of complement, for they found that anti-meningitis sera which were 

 freed from complement possessed bactericidal properties. Ecker has 

 made similar observations in regard to a serum specifically bacteriolytic 

 for the diphtheria bacillus. Nevertheless, Ecker found that the addi- 

 tion of complement increases the bacteriolytic action of this serum. 



The Pfeiffer phenomenon was found applicable to bacteria other 

 than the cholera spirilla, including particularly the typhoid bacillus, 

 paratyphoid, dysentery and colon bacillus. With these organisms the 

 phenomenon proceeds more slowly than with cholera spirilla. Were 



