104 BACTERIOLOGY. 



with free circulation of blood and retention in the body 

 of substances which should be eliminated also tend to 

 lessen the vitality. In these and other similar ways 

 animals which are otherwise refractory may acquire a 

 susceptibility to disease. 



Immunization and Healing by Non-specific Means. Just 

 as all conditions which are deleterious to the body lessen 

 its power of resistance to bacterial invasion, so all con- 

 ditions which are favorable to it increase its resistance, 

 and thus aid in preventing and overcoming infection. 

 The internal use of antiseptics against bacteria has 

 not proved successful, for the reason that an amount 

 too small to inhibit bacterial growth is found to be 

 poisonous to the tissue cells. The efficacy of quinine 

 in malaria and mercury in syphilis is, possibly, an ex- 

 ception to the rule, but in both cases we are dealing 

 probably with animal parasites, not ordinary bacteria. 

 Such substances as nuclein and others contained in 

 blood-serum, when introduced into the body in consider- 

 able quantity, aid somewhat in inhibiting or preventing 

 the growth of many bacteria. Even bouillon, salt 

 solution, and small amounts of urine have a slight in- 

 hibitory action. The hastening of elimination of the 

 bacterial poisons by free intestinal evacuation and en- 

 couragement of the functions of the skin and kidneys 

 are also of some avail. The enzymes formed by certain 

 bacteria have been found to exert a slight bactericidal 

 action, not only on the germs which have directly or 

 indirectly produced them in the body, but also on other 

 varieties. JSTone of these enzymes are sufficiently pro- 

 tective to be of practical value nor equal in power to the 

 protective substances formed by the tissues from the 

 bacterial products. 



