IN THE BLOOD AND TISSUES. 67 



perfectly free from vegetable germs. Some are, 

 however, not uncommonly met with on the free 

 surface of the germinal matter, where its death and 

 conversion into formed material are taking place. So 

 long as the higher living matter lives and grows, the 

 vegetable germs are passive and dormant, but when 

 changes occur and the normal condition departs, they 

 become active and multiply. Millions are always 

 present on the dorsum of the tongue and in the ali- 

 mentary canal, but they remain in what may be 

 termed a germ or embryonic state. The normal secre- 

 tions poured into the alimentary canal prevent their 

 growth, and the nourishment comes to us instead of 

 being appropriated by them. But what happens if 

 some of these fluids be suppressed or changed in 

 quality ? The bacteria grow and multiply, and the 

 nourishment is no longer absorbed into our bodies. 

 In infants a little derangement in digestion will 

 entirely prevent the assimilation of the milk, which 

 remains in the intestines a source of irritation, until it 

 is expelled, serving only for the nutrition of bacteria, 

 which are found in countless multitudes in every 

 particle of it. If more milk be introduced it soon 

 undergoes the same change, and the child might, 

 perhaps, be starved by the persistent introduction of 

 fresh food. If food is withheld for a time, the alimen- 

 tary canal soon becomes emptied of its contents, and 

 regains its natural healthy action, a process which is 

 expedited, as is well known, by the administration of 



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