18 IMMUNITY IN HEALTH 



intestines if only the gross pieces of faecal material have 

 been removed. And many a physician must have 

 wondered at the comparative harmlessness of coli 

 bacillaemia as evidenced by even extreme degrees of coli 

 bacilluria. * 



It may be noted, too, that the alimentary tract alone 

 i^ exposed to the bovine type of tubercle bacilli, and 

 that the incidence of bovine infection diminishes with 

 increasing age. 



