RESPIRATION 275 



like the rapidity of the pulse and for much the same reason. 

 When we work hard more oxygen is consumed and more 

 carbon dioxide is produced and the lungs, thus compelled 

 to become more active, require air to be pumped in 

 and out with greater rapidity. At the same time the 

 blood must be hurried through the lung capillaries in 

 order that it get rid of its surplus of carbon dioxide and 

 receive the requisite supply of oxygen for the increased 

 demands of the tissues. This is why .when we run hard 

 for a train we find ourselves panting for breath and our 

 pulse beating wildly; we become heated too as a result 

 of the increased metabolism that goes on in our muscles. 



As respiration is so intimately associated with the 

 maintenance of life it is especially important that we be 

 supplied with an abundance of fresh air. If we live in 

 small rooms into which air from the outside cannot freely 

 enter, the air supply soon becomes contaminated with 

 carbon dioxide and other noxious products. We soon 

 experience a sense of lassitude and depression, and if we 

 habitually live under such conditions our general health 

 will inevitably become impaired. Colds, consumption and 

 various other diseases are more readily contracted by 

 persons who live in impure air. Rooms should be ven- 

 tilated so as to secure a free circulation of air without 

 exposing their inmates to cold draughts. In order to 

 breathe properly the chest should not be allowed to become 

 deformed as it is in many people with stooping shoulders. 

 Students who sit at desks which are too low are par- 

 ticularly liable to this deformity. The chest capacity is 

 diminished and the whole body consequently suffers. 



Many women through the absurd habit of tight lacing 

 compress their bodies so that the lower part of the chest, 

 which normally expands most in breathing, can scarcely 

 expand at all. Consequently they breathe mostly with 



