IMMUNITY 8 1 



haptophores, by which the toxin molecule can become joined 

 to the cell; (2) the toxophores, by virtue of which it can attack 

 the protoplasm after having been fixed to it by the hapto- 

 phore. If the attack on the molecule is not too severe, this is 

 stimulated into overactivity and throws out an abnormal number 

 of receptors, some of which (the haptins) become detached 

 and are capable of uniting with free haptophores and prevent- 

 ing their combination with the protoplasm of the molecule. 

 In other words, they represent the antitoxin. 



Hemolytic Serum. The blood-serurn of some animals 

 has the power of destroying or dissolving the red corpuscles 

 of another animal of different species. This power can be 

 increased by repeated injections of blood-corpuscles, and is 

 allied to the bactericidal power. 



Bacteriolysis is the destruction of the bacterial cells by the 

 blood-serum, and is probably effected in a somewhat different 

 manner. Antibacterial serums are effective through the com- 

 bined activities of a destructive element, the "complement" 

 (alexin or cytase), and an " immune body" (amboceptor) , which 

 serves the function of joining the complement to the bacterial 

 molecule. These two bodies differ markedly in their properties 

 for example, the complement is destroyed at 60 C., while the 

 immune body is very resistant. 



It is not stated what cells are the sources of these various 

 antibodies, but probably any cell capable of being attacked by 

 a toxin is also capable of responding by the production of anti- 

 substances. 



Lysins. The substances producing destruction of bacteria 

 are called lysins. Normal blood-serum is bacteriolytic to a 

 slight degree, but during infection produces lysins specific for 

 the germ in question. 



Agglutinins. These are bodies formed in the blood-serum 

 in response to the stimulation of certain bacteria, such as the 

 typhoid bacillus, Bacillus coli communis, Micrococcus meli- 

 tensis, the bacillus of dysentery, the cholera spirillum, etc. 

 When such a serum is added to cultures of the particular organ- 

 ism concerned, the bacteria become clumped in motionless 



