STUFFY ROOMS 395 



evaporation from, and flow of tissue lymph through, the respiratory 

 tract, in warm, moist confined air. Colds are not caught by exposure 

 to cold per se, as is shown by the experience of Arctic explorers, sailors, 

 shipwrecked passengers, etc. 



We have very great inherent powers of withstanding exposure to 

 cold. The bodily mechanisms become trained and set to maintain the 

 body heat by habitual exposure to open-air life. The risk lies in over- 

 heating our dwellings and over-clothing our bodies, so that the mech- 

 anisms engaged in resisting infection become enfeebled, and no longer 

 able to meet the sudden transition from the warm atmosphere of our 

 rooms to the chill outside air of winter. The dark and gloomy days 

 of wmter confine us within doors, and, by reducing our activity and 

 exposure to open air, depress the metabolism; the influence of smoke 

 and fog, gloom of house and streets, cavernous places of business and 

 dark dwellings, intensify the depression. The immunity to a cold 

 after an infection lasts but a short while, and when children return, 

 after the summer holidays, to school and damp chill autumn days, 

 infection runs around. The history of hospital gangrene and its 

 abolition by the aseptic methods of Lister — likewise the history of 

 insect-borne disease — show the great importance of cleanliness in 

 crowded and much occupied rooms. The essentials required of any 

 good system of ventilation are then (1) movement, coolness, proper 

 degree of relative moisture of the air; (2) reduction of the mass influ- 

 ence of pathogenic bacteria. The chemical purity of the air is of very 

 minor importance, and will be adequately insured by attendance to 

 the essentials. 



As the prevention of spray (saliva) infection by ventilation is 

 impossible in crowded places, it behooves us to maintain our immunity 

 at a high level. We may seek to diminish the spray output of those 

 infected with colds by teaching them to cough, sneeze and talk with a 

 handkerchief held in front of the mouth or to stay at home until the 

 acute stage is past. 



In all these matters nurture is of the greatest importance, as well 

 as nature. A man is born with physical and mental capacities small 

 or great, with inherited characteristics, with more or less immunity to 

 certain diseases, with a tendency to longevity of life or the opposite, 

 but his comfort and happiness in life, the small or full development 

 of his physical and mental capacities, his immunity and his longevity 

 of life, are undoubtedly determined to a vast extent by nurture. By 

 nurture — use the the word in its widest sense to include all the 

 defensive methods of sanitary science — plague, yellow fever, malaria, 

 sleeping-sickness, cholera, hospital gangrene, etc., can be prevented by 

 eliminating the infecting cause; smallpox and typhoid by this means, 

 and also by vaccination; and most of the other ills which flesh is sup- 



