HEALTH AND DEVELOPMENT. 53 



have been hot and tired after severe exercise, and have felt 

 that the skin, which had been previously hot and dry, became 

 moist and cool from perspiration almost immediately after the 

 fluid had been swallowed. The rapidity of this effect, and 

 the fact that after a copious sweat, the drinking of a large 

 quantity of water will be followed by a comparatively small 

 increase in the amount of urine discharged, show that a con- 

 siderable portion of the water lost during exercise, is a 

 necessary part of the solids and fluids of the body, and con- 

 sequently no avoidable delay should occur in its replacement. 

 A full supply of water is not only necessary for removing 

 heat by evaporation, but also for keeping the bowels, kidneys, 

 and other organs in good working order. As the necessity 

 for the cooling effect of evaporation from the skin is propor- 

 tionate to the exercise taken, other things being equal, the 

 severer and more prolonged the exercise, the cleaner should 

 be the skin and the shorter should be the coat, so that as 

 little impediment as possible may be offered to the escape of 

 perspiration into the air. 



As long as exercise is continued, there is practically no 

 danger of chill. But if a horse is pulled up when hot from 

 work and is kept standing in a cold atmosphere without 

 anything being done to protect him from its bad effects, he 

 will be specially liable to catch cold ; because the cooling 

 process of evaporation will continue to remain unduly active 

 for a longer or shorter period, during which, the supply 

 of extra heat to the skin from the action of the muscles 

 will be cut off. 



Exercise improves the quality of the structures affected by 

 it, and disuse has the opposite effect. Thus we find that a 

 horse out of training is peculiarly liable to injury from 

 unwonted exertion ; not only because the muscles, tendons, 

 ligaments and bones of his limbs are wanting in strength and 

 resistance, but also because he will suffer far more severely 



