PHYSICAL TRAINING 151 



the treatment of disease by remedial exercises in 

 the open air. There are involved here far more 

 factors than pure air ; the influences are exposure 

 to changes of temperature, moisture and wind, 

 which produce physiological responses in the organ- 

 ism. The resistance is raised, and only thus can 

 the ravages of epidemics be avoided. A mild 

 attack of disease will lead to immunity. It is 

 impossible, even if it were desirable, to abolish 

 disease and death, but it is possible to increase 

 greatly the resistance of a nation to the diseases 

 which are common in the country. 



Thus far the subject of physical training and 

 the open-air life has been considered from a general 

 standpoint, and the arguments brought forward are 

 such that the layman can estimate their worth. 

 It will be convenient now to show the agreement 

 of physiological knowledge with the experience of 

 athletes, sportsmen and labourers. Such a com- 

 parison will be obtained most readily by a con- 

 sideration of the different systems of the body in 

 relation to physical training and life in the open air. 

 ^ ^V' The Circulation of the Blood. — The heart, the 

 p#^^ pump which drives the blood round the body, is 

 one of the most important factors concerned in 

 physical training. It pumps the blood through the 

 lungs, and in this respect is an essential component 

 of a '' good wind," for it is useless to ventilate the 

 lungs if the blood does not circulate rapidly enough 



