AVENUES OF EXIT OF INFECTIOUS AGENTS. 157 



the fact that there are as many infectious processes 

 locahzed in the intestinal tract as in the air-passages, in 

 all of which the microbes are eliminated in the stools, 

 the germs of every general disease find their way into 

 the same passage by way of the bile. Furthermore, 

 a host of animal parasites are found sporadically in the 

 intestinal tract from which they or their eggs escape 

 by the natural passages. With one exception, i.e., in 

 consumption, the sputum is chiefly dangerous to those 

 immediately surrounding the patient; and even in this 

 disease the infection is mostly limited to dwellings, 

 factories, and offices. The feces, on the contrary, are 

 the source of certain wide-spread infections at great 

 distances from the patient. This happens because the 

 micro-organisms causing these diseases are capable of 

 growth outside the body, particularly in water, and 

 because they are such as must be taken into the alimen- 

 tary canal to produce their effects. 



In the matter of disposal of sewage we are still bar- 

 barians, if not criminals ; and the diffidence with which 

 the public views the pollution of its water-supply by 

 alvine discharges is a shame to our much vaunted 

 civilization. In fact, it is little short of miraculous that 

 a stop has not been put to it long ago, when one con- 

 siders the wide publicity given to the actual and possible 

 dangers of such a filthy and obnoxious practice. But 

 it is permitted to go on, with the result that there is 

 scarcely a city or town that does not drink water which 



