94 INFECTIONS OF THE DIGESTIVE TRACT 



into the mucous membrane. How far the presence 

 of mucus on the surface of the epithelial layer is a 

 factor in rendering the mucous membrane impermeable 

 is still a question. It appears from the work of 

 Hilgermann 1 and others that the normal mucous 

 membrane is much more permeable to some bacteria 

 during the period of infancy than in later life. It was 

 found by Hilgermann that when young rabbits and 

 guinea-pigs are fed with tubercle bacilli, these organisms 

 pass through the wall of the stomach and penetrate 

 the digestive tract throughout its entire extent. It 

 was noticed that the number of bacteria passing through 

 the small intestine, especially in its upper third, was 

 considerable, whereas the number which penetrated the 

 wall of the large intestine was much smaller. In the 

 vermiform process the conditions for the passage of 

 tubercle bacilli appear to have been the same as in the 

 case of the small intestine. 



Hilgermann attempted to determine what factors 

 are concerned in the passage of tubercle bacilli through 

 the digestive tract in animals. He was at first inclined 

 to regard the passage as accidental and due to small 

 lesions, but this view was abandoned because it was found 

 that the penetration did not occur at single points, but 

 throughout the length of the gastro-enteric tract. It 

 was found, moreover, that there is no evidence of pene- 

 tration occurring in corjsequence of an irritation by a 

 considerable number of bacteria acting locally. If this 



x "Die Bakteriendurchlassigkeit der normalen Magendarm- 

 pchleimhaut im Saulingsalter," Archiv f. Hyg., liv, p. 335, 1905. 



