160 INFECTION AND IMMUNITY 



they become active agents in the transmission of this 

 infectious disease "the great white plague"- which 

 is responsible for twelve per cent, of the deaths 

 which occur within the limits of the United States. 

 The last census report shows that in the census 

 year, 1900, 109,750 deaths occurred from pulmonary 

 consumption. This is a smaller number in proportion 



FIG. 5. Bacillus of tuberculosis, as seen in the sputum of a patient having 

 pulmonary consumption ; magnified 1000 diameters. 



to the population than occurred in 1890. A decided 

 gain is shown during recent years by the mortality sta- 

 tistics of some of our large cities, in which special ef- 

 forts have been made to instruct the public as to the 

 method in which the disease is propagated, to prevent 

 expectoration in public places, and to disinfect the 

 sputa of recognised cases of pulmonary tuberculosis. 

 New York City, under the able leadership of Dr. 



