4 INFECTIONS OF THE DIGESTIVE TRACT 



either essential or non-essential to the maintenance of 

 prolonged health during the period of adult existence. 

 The evidence given by the sterile intestinal contents 

 of certain Arctic animals is apparently conclusive for 

 the conditions in which this experiment of nature has 

 been carried out. Here we have animals born and living 

 in surroundings where bacteria are very few in number, 

 and it is probably on account of the great rarity of micro- 

 organisms in the air and the small number in the water l 

 that the intestinal contents contain so few bacteria. 

 These animals are able to live indefinitely in a state of 

 robust health. Levin examined the intestinal contents 

 of Arctic animals in Spitzenberg. The digestive tract 

 was found to be in most instances entirely sterile in 

 white bears, seals, reindeer, eider ducks, penguins, etc., 

 although very small numbers of organisms resembling 

 the colon bacillus were found in one white bear and in 

 two seals which were examined. 



Clearly then, in this case, the intestinal bacteria are 

 not required to carry on the ordinary digestive processes 

 and normal nutrition. It has been supposed that the 

 intestinal bacteria aid in the digestion of cellulose, which 

 they are undoubtedly able to decompose fermentatively. 

 The argument in favor of the importance of this function 

 of the intestinal bacteria loses much of its force if it be 

 true, as lately maintained by Bergman, 2 that most of the 



1 It was estimated that there was one organism in 11 c.c. of 

 water, whereas in the river Seine it was estimated that there are 

 about 2,000,000 in the same volume of water. 



2 "Studien tiber die Digestion der Pflanzenfresser," Skandir 

 navisches Archiv /. Physiol., xviii, p. 119, 1906. 



