AND ITS EFFECTS UPON ANIMAL LIFE. 27 



tive appai'atus, and it is due, in [uirt, to volatile fatty acids given o(l' with, or 

 produced from, the excretions of the skin, and from clothing soiled with 

 such excretions. It may produce nausea and other disagreeable sensations in 

 specially susceptible pei'sons, but most men soon become accustomed to it, and 

 cease to notice it, as they will do with i-egard to the odor of a smoking-car, or of a 

 soap factory, after they have been for some time in the [>Iace. The direct and 

 indirect effects of odors of vai'ious kinds upon the comfort, and i)erhaps also u[)()n 

 the health, of men are more considerable than would be indicated Ijy any tests 

 now known for determining the nature and quantity of the matters which give rise 

 to them. The remarks of Rank (38, p. 174) upon this [H)int meiit consideration. 

 Cases of fainting in crowded rooms usually occur in women, and are connected 

 with defective respii'atory action due to tight lacing or other causes. 



Other causes of discomfort in rooms heated by furnaces or by steam are exces- 

 siv^e dryness of the air, and the presence of small quantities of carbonic oxide, of 

 illuminatiua; gas, or of arsenic derived from the coal used for heating. 



XI. The results of this investigation, taken in connection with the results of 

 other recent I'esearches summarized in this report, indicate that some of the theories 

 upon which modei'n systems of ventilation are based are either without foundation 

 or doubtful, and that the problem of securing comfort and health in inhabited 

 rooms requires the consideration of the best methods of preventing or disposing of 

 dusts of various kinds, of propei'ly regulating temperature and moisture, and of 

 preventing the entrance of poisonous gases like carbonic oxide derived from heat- 

 ing and lighting apparatus, rather than upon simply diluting the air to a certain 

 standard of propoiliou of carbonic acid present. 



It would be very unwise to conclude, from the facts given in this report, that 

 the standards of air supply for the ventilation of inhabited rooms, which standards 

 are now generally accepted by sanitarians as the result of the work of Pettenkofer, 

 De Chaumout, and others, ai'e much too large under any circumstances, or that the 

 differences in health and vigoi- between those who spend the greater part of their 

 lives in the open air of the country hills, and those who live in the city slums, do 

 not depend in any way upon the differences between the atmospheres of the two 

 localities except as regards the number and character of micro-organisms. 



