ANAPHYLAXIS ^ 295 



this work, even though they are the ones which suffer the 

 greatest injury in disease. Hence it is to be expected that 

 the lower or unspeciahzed cells are the source, and it has 

 been shown that the antibodies are produced by the phago- 

 cytes (though not entirely as Metchnikoff maintained), by 

 lymphoid tissue generally, by the bone-marrow and also by 

 connective-tissue cells, though in varying degrees. 



Since immunity depends on the activity of the body cells, 

 it is evident that one of the very best methods for avoiding 

 infectious diseases is to keep these cells up to their highest 

 state of efficiency to keep in "good health." Hence good 

 health means not only freedom from disease but also protection 

 against disease. 



