Page:Popular Science Monthly Volume 66.djvu/453

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NALYSIS of vital statistics for the last three-quarters of a century shows an average increase in the duration of human life among civilized peoples from 42.2 years to 48.5 years. The chief increase has been during the latter half of that period, and, for the most part, by the reduced mortality from zymotic diseases, but, above all, from pulmonary tuberculosis, from which the reduction of mortality has been nearly fifty per cent.

Inquiry with regard to the means by which this reduction has been effected, shows it to have been almost wholly by sanitary efforts; by dealing with and destroying unsanitary surroundings, soil-drainage, purifying water supplies, reporting and restricting communicable diseases, sanitary supervision of schools, the destruction of sputum—the now everywhere recognized fountain-head from which the army of bacilli is perpetually reinforced—abolishment of cellar-dwellings, diminished overcrowding, cleanliness, disinfection, isolation and aeration; improved tenements, opened-up and wider streets, public parks and recreation grounds and establishment of sanitaria. This catalogue of sanitary efforts might be still further extended, though altogether without record of special effort for improved nutrition except for nursing infants.

Communicable as all competent observers know tuberculosis to be, while they equally well know that it is not so under all circumstances, it is indeed questionable whether any one of sound constitution and well nourished has ever contracted the disease from nursing consumptives, or from living with them otherwise, under good hygienic surroundings.

On the contrary, no matter how healthful the surroundings or the salubrity of the atmosphere, for poorly nourished and feeble persons, from whatever cause, there is no immunity from tuberculosis. For no one who even approximately comprehends the universality of microbic life—and of none more than tubercle bacilli—can fail to perceive that, however much we may be able to modify the external relations bearing upon liability to tuberculosis, nevertheless every