ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 331 



vulnerability by typhoid and pneumonia. Cultivation of whatever 

 germs there may be in stinking air from old drains, middens, putrid 

 sink water, etc., and identification of disease germs if possible. 



DIPHTHERIA. 



Examination of air for detection of the diphtheria bacillus over 

 polluted surfaces of sandy soil, over ash heaps, decaying vegetable and 

 animal matter, and above drain outlets. Eelation of the bacillus to 

 atmospheric conditions where it grows on soil, organic matter, dirty 

 floors, or walls, etc.; how far it is aerobic; how far it may pass through 

 air in different conditions, and how much it loses virulence in dry air, 

 in moist air, and in confined and open spaces. Effect of exposure or 

 aeration in causing it to form spores, if any. Effect of sunshine on 

 the bacilli, with and without air; the diphtheritic poison is rapidly 

 weakened by air with sunshine, but only slowly by sunshine alone. 

 Effect of coating a cultivation of diphtheria bacilli with a very thin 

 film of oil or viscous disinfectant, so as to prevent growth and passage 

 into the air. The favorable temperature, a rather low one, the exclu- 

 sion from light and air, and the presence of certain other organisms 

 furnish useful points of departure for an investigation of climatic and 

 local conditions of prevalence of diphtheria. 



SCARLET FEVER, MEASLES, WHOOPING COTJG-H, INFLUENZA, AND 



SMALLPOX. 



Distance through which each of these diseases has been known to 

 pass in air in various conditions. Experiments especially with respect 

 to vaccine in relation to the conveyance of smallpox through long dis- 

 tances of outer air. Accumulation of experience and new observations 

 on the virulence of the lymph in dry and humid air, and a comparison 

 with the virulence of pathogenic bacilli of different kinds exposed to 

 like surroundings. Dependence of most of these diseases on air in 

 confined and ill- ventilated spaces for effective spread. How far can 

 ventilation, and how far can diffusion of ozone, disinfectants, and vari- 

 ous aromatic substances and vapors counteract the infectivity of the 

 germs ? 



INFECTIOUS, CONTAGIOUS, EPIDEMIC, AND ENDEMIC DISEASES IN 



GENERAL. 



A full investigation into the comparative health of persons living in 

 fairly isolated places, such as islands or institutions having little com- 

 munication with populous places, would lead to useful results. The 

 occasions of any outbreak of disease could probably be accounted for 

 and the medium of conveyance identified. The degree of human sus- 

 ceptibility to various infections could be much better made out than in 

 ordinary situations. Moreover, those diseases, such as bronchitis, rheu- 

 matism, and cancer, which do not seem to depend for the most part on 



