136 INFECTION AND IMMUNITY 



infected water used to dilute the milk or to wash the 

 vessels containing it. 



The bacillus of typhoid fever is a rod-shaped micro- 

 organism, about one fifty-thousandth of an inch thick 

 (from five- to eight-tenths of a micro-millimetre) and 

 from two to six times as long as it is broad ; it also 



FIG. 3. Bacillus of typhoid fever ; magnified 1000 diameters. 



grows out into long thread-like filaments. The mi- 

 nute size of this and other similar disease germs will 

 perhaps be better appreciated when we say that one 

 cubic centimetre of urine from a typhoid patient has 

 been found to contain as many as 1 72,000,000 typhoid 

 bacilli estimated by a counting method well known 

 to bacteriologists. 



This bacillus was first observed in 1880 by the 

 German physician and bacteriologist, Eberth, and in- 



