r& INFECTIONS OF THE DIGESTIVE TRACT 



to the epithelial and other structures of the intestinal 

 mucous membrane, these anaerobes are gradually afforded 

 more and more favorable opportunities for their growth. 



As to the relation between the relatively active anaerobic 

 life in the intestine during senility and the development 

 of the involutional alterations in the tissues, it is difficult 

 to formulate an opinion. Many factors may doubtless 

 enter into the production of these cellular alterations, and 

 it is difficult to assign to each of these its just position. 

 One statement may, however, be confidently made: 

 the onset of senility may be distinctly accelerated through 

 the development of intestinal infections in which the 

 putrefactive anaerobes are prominently represented. 

 I have observed this in cases where it has appeared to 

 me a certainty that other toxic causes of premature 

 senility could be excluded. 



The view that intestinal infections stand in a causative 

 relation to old age is by no means new. It has been 

 advanced by Metchnikoff on several occasions. It is 

 probable that the "wild races" of bacteria of which 

 he speaks as responsible for senile changes consist largely 

 of putrefactive microorganisms. I do not know that 

 Metchnikoff has singled out any definite group of micro- 

 organisms as especially concerned. I am inclined to give 

 prominence to B. aerogenes capsulatus as the most impor- 

 tant factor in the production of the putrefactive decom- 

 positions of advanced age. It is extremely probable 

 that persons with apparently equal numbers of gas- 

 bacilli in the intestinal tract do not necessarily suffer an 

 equal degree of harmful influence from their putrefactive 



