METHODS OF VENTILATION 185 



Methods of ventilation. Many systems of ventilation have been 

 devised, but probably in many places none works as efficiently as 

 properly regulated windows. Windows should be opened at the 

 top and bottom during both day and night. Air comes in the 

 lower opening, becomes heated, rises, and goes out through the 

 upper openings. Care should be taken that drafts are kept out 

 of the room since these are likely to chill the body. A board 

 placed at the bottom of an open w indow can be arranged so as to 

 drive the air upward and will thus prevent drafts. In winter, 

 care must be taken to keep the air moist. If the air is too dry, 

 the mucous membrane lining of the nose and throat will become 

 dry and irritated, probably resulting in inflammation in the res- 

 piratory tract. The various methods of heating homes are likely 

 to dry the air. The evaporation of water in pans placed under 

 or on radiators will aid greatly in moistening the air. To-day, 

 we find that ventilating systems are included in many of the 

 modern heating plants. In these systems the same air is circu- 

 lated repeatedly. It is washed, heated or cooled, and freed of 

 moisture in each circuit. 



Hygiene of respiration. A great many deaths are caused an- 

 nually by diseases of the respiratory tract. Many of these could 

 be prevented if the respiratory tract were kept in good condition. 

 The nose is adapted for preparing the air for the use of the 

 body, and, therefore, it should be used for breathing. Any inter- 

 ference with nasal breathing should be corrected. 



Questions and Suggestions 



1. Suggest two experiments that may be used to show that oxida- 

 tion takes place in the body. 



2. Name the adaptations of the respiratory system for (a) puri- 

 fying air, (b) warming air, (c) moistening air. 



3. Make a labeled diagram of the air passages. Trace the path 

 of air from the time it first enters the body until it reaches the 

 cells. 



WH. FITZ. AD. BIO. — 13 



