152 AGE-INCIDENCE Otf CAUSES OF INFANT MORTALITY 



fatal to summer-born, city-bred infants, not breast-fed. It is 

 least fatal to winter-born infants, wholly breast-fed. It is the 

 unique distinction of this epidemic that it searches out and at- 

 tacks solitary infants, and is neither preceded nor followed by 

 like sickness among older persons in immediate contact. It oc- 

 curs during the period of adaptation of the gastro-intestinal tract 

 to the permanent support of an abundant and varied bacterial 

 flora. In proportion as this adaptation is hastened, the hazard 

 is compounded. 



