68 ILLINOIS ACADEMY OF SCIENCE 
pneumococcus was to be found in the oral and respiratory 
passages of a large proportion of healthy individuals, and 
that the lowering of the vitality by exposure to cold, by inhala- 
tion of dust and fumes, alcoholism, injury to lung tissue, or 
senility so disturbed the balance between the virulence of the 
organism and the susceptiblity of the individual as to present 
a favorable opportunity for development of the disease. This 
conception does not agree with recent observations, which 
seem to indicate that the disease is due to contact with patients 
or with healthy carriers. 
The prevention of pneumonia requires isolation of the pa- 
tient, disinfection of his expectoration, and the avoidance of 
all things which tend to lower the vitality of the individual or 
to favor the spread of the disease by carriers. The increased 
opportunity for infection in cities owing to crowding demands 
the allaying of dust, and adequate ventilation of theaters, 
schools, cars and public buildings. Occupations requiring ex- 
cessive fatigue, exposure to unsuitable temperatures, and to 
dust or fumes should be under the supervision of a sanitarian 
and so modified as not only to add to the efficiency of the 
worker, but to afford him an opportunity to increase his re- 
sistance to disease. The occurrence of pneumonia may be 
reduced, individual susceptibility decreased, and the devitaliz- 
ing influence of modern life successfully overcome by proper 
exercise, the abundance of fresh air at night, as well as during 
the day, sunlight, sensible clothing, sufficient and suitable 
food, cold baths, enough sleep, attention to oral hygiene and 
by the avoidance of exposure, excessive fatigue and alcohol. 
Tuberculosis caused 147,000 deaths in 1913. The mortal- 
ity rate of tuberculosis has markedly declined, falling from 
326.2 per 100,000 population in 1880 to 147.6 in 1913. The 
decrease has been uninterrupted since 1904. There are ap- 
proximately a million and a half individuals suffering from 
tuberculosis in the United States. 
The medical profession and the public have more consist- 
ently endeavored to prevent tuberculosis than probably any 
communicable disease, but, in spite of their efforts, it is of 
the first importance among the causes of death and is still "The 
Great White Plague," the captain of the hosts of death. 
