206 A MANUAL OF BACTERIOLOGY 







immunised and yields a serum which possesses a certain 

 amount of protective and curative power. The name of 

 anti-microbic serum or anti-serum is given to such a 

 serum. 



To this class belong the anti-streptococcic, anti- 

 pneumococcic, and anti -plague sera. The usual mode of 

 preparation is to commence the inoculation of the animal 

 with killed culture, gradually increasing amounts of 

 which are given until a large dose is attained. Living 

 culture is then given, commencing with a small dose and 

 gradually increasing the amount at each injection. After 

 a course of treatment extending, it may be. over several 

 months, the serum acquires its maximum potency when 

 the animal is bled and the serum bottled, as in the case 

 of antitoxic sera. The anti-microbic sera are not nearly 

 so active as antitoxic sera, and for curative use are on the 

 whole disappointing. 



An anti-microbic serum will protect an animal against 

 the corresponding living microbe within certain limits, 

 but the protection afforded is not strictly proportional 

 to the amount of serum used. 



For example, if 0-005 c.c. of anti-cholera serum protects 

 against 5 mgrm. of living cholera culture, three times as 

 much, or 0-015 c.c., of the serum will probably not protect 

 against 15 mgrm. of cholera culture, and when a certain 

 dose of the culture is reached no amount of serum will 

 save the animal. 



The mode in which the anti-serum acts may be studied 

 microscopically. If cholera anti-serum and cholera 

 culture be injected into the peritoneal cavity of a guinea- 

 pig, and the peritoneal contents be examined at short 

 intervals afterwards, it will be found that the vibrios lose 

 their motility, become distorted and globular, undergo 

 solution, and finally disappear. The protection afforded 

 by the anti-serum is therefore due to the destruction of 



