. Essentials de biologie a présenté des problèmes. La biologie. La SANTÉ ET LA MALADIE 419 En plus du dioxyde de carbone, d'eau et de chaleur sont émis ainsi qu'une très petite quantité de matière organique d'un caractère toxique. C'est la présence de ce matériau qui donne lieu à l'odeur perceptible dans une chambre étroite. Mais d'autres matières organiques est présent dans l'air. La poussière de la rue contient des bactéries de toutes sortes, dont certains peuvent être des. Ce qui peut l'être de bactéries de l'appareil respiratoire des personnes qui ont le rhume, la pneumonie, la diphtérie, ou la tuberculose. Beaucoup de poussière est séché. Deux cultures

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. Essentials of biology presented in problems. Biology. HEALTH AND DISEASE 419 In addition to the carbon dioxide, water and heat are given off as well as a very small amount of organic material of a poisonous nature. It is the presence of this material that gives rise to the odor noticeable in a close room. But other organic material is found in air. Dust from the street contains bacteria of all kinds, some of which may be disease-producing. Thus may be spread bacteria from the respiratory tracts of people who have colds, pneumonia, diphtheria, or tuberculosis. Much dust is dried. Two cultures (A) were exposed to the air of a dirty street in the crowded part of Manhattan. (B) was exposed to the air of a well-cleaned and watered street in the uptown residence portion. Which culture has the most colonies of bacteria ? How do you account for this ? excreta of animals. Soft-coal smoke does its share to add to the impurities of the air, while sewer gas and illuminating gas are frequently found in sufHcient quantities to poison people. Pure air is, as can be seen, almost an impossibility in a great city How to get Fresh Air. — As we know, green plants give off in the sunlight considerable more oxygen than they use, and they use up carbon dioxide. The air in the country is naturally purer than in the city, as smoke and bacteria are not so prevalent there, and the plants in abundance give off oxygen. In the city the night air is purer than day air, because the factories have stopped work, the dust has settled, and fewer people are on the streets. The old mjrth of " night air " being injurious has long since been exploded, and thousands of people of delicate health, especially. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Hunter, George William, 1873-1948. New York, Cincinnati [etc. ] Ameri

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