288 BACTERIOLOGY 



Second, there are the antitoxins, found in the blood of 

 animals artificially immunized from special sorts of intox- 

 ication, 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, bacteriolytic 

 powers, a bacteriolysin — i. e., having the property of actually 

 dissolving bacteria, so that the phenomenon may be observed 

 under the microscope. This phenomenon, generally known 

 as "Pfeffer's Phenomenon," is especially to be seen within 

 the peritoneum of guinea-pigs that have been rendered im- 

 mune from Asiatic cholera and from the typhoid and colon 

 infections and intoxications. 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 presence of this 

 body in a serum of an animal is announced by its peculiar 

 influence on the activity and arrangement of the particular 

 species of bacteria from which the individual is immune, or 

 with which it is infected. In the case of typhoid fever in 

 man, for instance, the serum obtained during the early and 

 middle stages of the disease, when mbced with fluid cultures 

 or suspensions of the typhoid bacillus, causes the bacilli to 

 lose their motility and to congregate (agglutinate) in masses 

 and clumps, a condition never seen in normal cultures of 

 this organism, and practically never observed when normal 

 serum is employed instead of the typhoid serum. The 



