578 BACTERIOLOG Y. 



have given to the blood and fluids of the body a new 

 and peculiar interest. According to circumstances, there 

 may be detected in the blood and tissue-juices a number 

 of bodies having totally different functions and affinities, 

 and therefore presumably different from one another. 

 To summarize briefly : First, there is normally present 

 in the blood-serum of practically all animals the de- 

 fensive "alexins" already mentioned. 



Second, the antitoxins that are found in the blood of 

 animals artificially immunized from special sorts of in- 

 fection and intoxication, as well as occasionally in the 

 blood and tissues of normal animals, the functions of 

 which are susceptible of demonstration outside the body 

 as well as within the tissues of the living animal. 



Third, a body possessed of disintegrating, bacterio- 

 lytic powers, a bacteriolysin /. e., having the property 

 of actually dissolving bacteria, so that the phenomenon 

 may be observed under the microscope. This phenom- 

 enon is especially to be seen within the peritoneum of 

 guinea-pigs that have been rendered immune from 

 Asiatic cholera and from the typhoid and colon infec- 

 tions and intoxications. 1 It is not to be confounded 

 with the ordinary bactericidal function of the alexins 

 that is demonstrable in most normal serums. 



Fourth, a body, the so-called " agglutinin " (Gruber), 

 that was considered by Widal to represent a "reaction 

 of infection," and not of immunity ; though at this time 

 its presence is generally supposed to indicate an effort 

 on the part of the body to resist infection. The pres- 

 ence of this body in a serum of an animal is announced 



ception in so brief a summary as is appropriate to a text-book. To be 

 appreciated it must be read as it came from its authors 

 i It is generally known as Pfeiffer's phenomenon. 



