162 PHYSICLOGY OF ALIMENTATION. 



total number of bacteria voided in twenty-four hours can be 

 calculated. For this figure GILBERT and DOMINICI give as an 

 average 12,000 to 15,000 millions; SucKSDORFF55 ; 000 millions; 

 KLEIN/ who probably used the best technique of the three, 

 8,800,000 millions. 



3. The weight of the bacteria excreted in twenty-four hours 

 has been calculated by Kx-EYN, 2 who estimates that 1.13 per- 

 cent of the dry faeces is made up of micro-organisms and that 

 about 293 milligrams are cast off in twenty-four hours. 



4. As to the kinds of bacteria inhabiting the alimentary 

 tract, the following may be said. We must distinguish first 

 of all between those bacteria which are almost constantly 

 present in the digestive tube and those which are present 

 only under certain circumstances. Under the latter head- 

 ing we can say that practically every known form of micro- 

 organism has been found in some portion of the intestinal 

 tract at some time. A large number of saprophytic bacteria 

 are always found in the mouth. After inhaling the air of 

 rooms in which infectious diseases have been housed, the 

 bacteria characteristic of that disease have been recovered 

 from the mucous membranes of the mouth, throat, and nose 

 of those who have lived in these rooms. But even from 

 the noses and mouths of persons following the ordinary rou- 

 tine of life have virulent pathogenic bacteria been culti- 

 vated. This has been done repeatedly for the ordinary pus 

 organisms, and NOBLE W. JONES has shown that virulent 

 tubercle bacilli are not uncommon inhabitants of these regions. 

 For the most part these, even pathogenic, bacteria are of 

 little or no importance. When, however, the health of the 

 individual as a whole, or the resistance, as we are pleased 

 to call it, of the tissues inhabited by these micro-organisms 

 is reduced through any cause whatsoever, they are able to 

 produce their characteristic pathological effects. 



The oesophagus harbors practically the same bacteria that 



1 KLEIN: Centralbl. f. Bakt., 1899, XXV, p. 278. 



2 KLEYN: Cited from KOHLBRUGGE, 1. c. 



