ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 257 



From these figures the effect of the breathing of foul air on res- 

 piratory diseases is conspicuous. But the differences represented 

 would have been much greater if the class described as living in pure 

 air had not been subject, during that part of their lives which was 

 spent within doors, to the bad air of close apartments or cabins, and to 

 the occasional infection of places of assembly and resort. 



That demonstrable bacilli are given out by the breath of persons 

 suffering from consumption and other diseases, has been proved by 

 Kansome and others. The possibility was doubted by Cornet and 

 other authorities on the grounds that nonvolatile substances can not be 

 exhaled, that many good observers have failed to find them, and that 

 where observed errors may have crept into the experiments. But 

 Cornet himself has shown that the bacilli are exhaled in small numbers 

 by patients, and that they and their spores are given off in great num- 

 bers from handkerchiefs, bed linen, furniture, floors, etc., of rooms in 

 which consumptive persons live. 



Klein has shown that guinea pigs exposed to a spray of tubercular 

 matter in the air, or else kept in the shaft of a ventilator in a consump 

 tion hospital, acquire the disease. It has been proved by Straus that 

 nurses of consumptive patients have tubercle bacilli deposited on their 

 breathing organs. These last experiments are not proofs of the exha- 

 lation of the fatal microbes. But we have the most convincing proof 

 in everyday facts of the possibility of the exhalation of the bacilli or 

 germs of several infectious maladies. The breath is one of the most 

 common vehicles of transference of infection from person to person. 

 Moreover, Ransome finds much indiffusible organic matter, such as 

 epithelial scales, in the condensed aqueous vapor of the breath. The 

 breath of consumptives, however, contains very few bacilli, and the 

 particles of sputum which fall from the mouth in expectoration or in 

 speaking are more dangerous. 



Tuberculosis has been produced in animals by causing them to inhale 

 air vitiated by subjects of phthisis. Glass slides, wetted with glycerin, 

 show the presence of tubercle bacilli in the air of consumption hos- 

 pitals. Tuberculous particles inhaled are found to be more capable of 

 infecting than particles swallowed. The air does not often, at any rate, 

 convey infection from the mere breath of a patient in an ordinary clean 

 room, and the temperature must be rather high to maintain the vitality 

 of the germ. In hot climates, under similar conditions, the danger is 

 greater, but generally the better ventilation reduces it. 



Consumption and leprosy are caused by similar microbes, and have 

 much in common in their behavior. In phthisis the contaminated air 

 conveys the bacillus to the air passages, and in scrofulous glands to the 

 nearest sore; in leprosy the exposed parts, hands, face, and feet, which 

 have received some scratch or wound, are first attacked. As leprosy 

 has been got rid of not only by improved conditions of living, but by 

 segregation of the victims, so consumption and tuberculosis will be 

 exterminated wherever the utmost care is taken in providing for fresh 

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