ALEXINS (COMPLEMENTS) 



II 



tralize the special toxins for which they have an affinity. Such an animal 

 is in a condition of active immunity, having itself produced the immu- 



r re e Receptors th<tf 

 have become M 

 Antitoxins 



Fig. 9. Toxins attached to receptors ; free receptors (antitoxins] ; antitoxins united with toxins. 



Alexin 

 (Complement) 



Amboceptor 

 (immune body) 



Receptor 



nizing agents ; it has a serum, however, that may be introduced into 

 another animal, rendering it passively immune. Both active and passive 

 immunity are antitoxic, as distinguished 

 from bacteriolytic immunity, in which lat- 

 ter, bacteria are dissolved and destroyed. 

 Cytolysis. The serum of one species 

 of animal injected into the vessels of 

 an animal of different species may dis- 

 solve the red corpuscles of the second 

 animal. This is called laking of blood ; 

 and the serum is then said to be lytic. 

 This, however, is not true of the Guinea 

 pig and the rabbit; but the serum of 

 the Guinea pig may be adapted to the 

 blood of the rabbit and rendered lytic 

 for such blood. This is called hemo- 

 lysis; and the Guinea pig's serum which 

 has been rendered lytic for rabbit's Fig . I0 ._^/r/* (complement) com- 

 corpuscles is lytic for these and for no * ined Wlth the receptor through the a,,,bo- 



ceptor (immune body) . 



other corpuscles. 



Alexius (Complements}. The lytic properties of the Guinea pig's 

 serum for rabbit's corpuscles may be neutralized by exposing it for half 



