76 INFECTIONS OF THE DIGESTIVE TRACT 



of indol in the intestinal contents (perhaps one or two 

 milligrams in one hundred grams faeces) a few milligrams 

 of phenol, and no skatol. The urine is free from indican 

 almost habitually, and only moderate quantities of 

 phenol are excreted (twenty to forty milligrams in 

 twenty-four hours). The ethereal sulphates are corre- 

 spondingly low. The dimethylamidobenzaldehyde re- 

 action is feeble or moderate in intensity. 



Persons of this type are apt to die at an advanced age 

 of some condition apparently quite distinct from disease 

 of the digestive tract, especially thrombosis of cerebral 

 vessels (from atheroma) or chronic myocarditis. 



I have not had a wide experience in the careful study 

 of the bacterial conditions in persons above sixty-five 

 years of age, but believe it safe to say that a large majority 

 of such persons (perhaps seventy per cent, of the popula- 

 tion in the United 'States above this age) give evidence 

 of distinct putrefactive processes in the digestive tract. 

 These processes are in many instances characterized by 

 their mildness. But if we compare these mild processes 

 of putrefaction with those existing in the majority of 

 persons under twenty years of age, we find a distinct 

 difference between the two. I think it quite clear that 

 the conditions in youth are much more close to the ideal 

 physiological state of infancy and childhood than are 

 those of senility. The difference lies mainly in the 

 direction of the greater abundance of putrefactive 

 bacteria in old age, but with this there is apt to be some 

 diminution in the number of typical colon bacilli, if 

 we may form a judgment on this point from the appear- 



