THE BACTERIA OF THE ALIMENTARY TRACT. 167 



doubt plays an important role. Again, the time which the 

 food spends in this part of the intestinal canal is far greater 

 than that in any of the preceding portions, so that the 

 time allowed for the multiplication of the bacteria is cor- 

 respondingly greater. We must, moreover, remember the 

 antiperistaltic movements of the transverse and ascending 

 colon as a potent factor in carrying the bacteria from the 

 descending arm of the large bowel into the transverse and 

 ascending portions of the colon. Bacteria are constantly 

 entering the alimentary tract by way of the rectum. Until, 

 however, we are better acquainted with the physiology of 

 the development and growth of bacteria, we can expect 

 to make but little progress in this as well as in other branches 

 of bacteriology. Systematic studies of the influence of 

 external conditions upon bacteria, such, for example, as 

 WILLIAM B. WHERRY 1 has recently begun on cholera and 

 which promise so much in the advance of our knowledge of 

 mycotic diseases, are still very rare. 



The question naturally suggests itself as to how the bac- 

 teria get from the mouth into the large bowel if the stomach 

 through which all the food passes has such well-marked 

 bactericidal action. We answer this question at present 

 by saying that the bacteria are either not all killed, that 

 they pass through in the form of spores, or finally, that 

 they are not affected by the gastric juice because they are 

 enclosed in particles of food. But even the practically 

 empty intestinal tract of starvation is not entirely free 

 from bacteria, from which the conclusion has been drawn 

 that the intestine has a flora of its own. Great care must, 

 however, be exercised in accepting this view, as it has not 

 yet been proved that the various bacteria found in star- 

 vation are not such as are capable of living on the secre- 

 tions of the intestinal mucosa alone. As these secretions 

 are different in different portions of the intestine it is not 



1 WHERRY: Journal of Infectious Diseases, 1905, II, p. 309. 



