SUMMARY. 323 



because it stimulates the leucocytes to increased 

 phagocytosis. 



4. Natural immunity to toxins depends on the 

 power of the leucocytes, and perhaps the genera- 

 tive organs, to absorb the toxin. 



5. Active immunity to toxins is established 

 through the activity of the leucocytes, by which 

 the toxin is probably so changed as to constitute 

 antitoxin. 



6. In passive antitoxic immunity the antitoxin 

 presumably acts by stimulating the phagocytes to 

 an increased absorption of the toxin. 



