284 PHYSIOLOGY AND HEALTH. 



hard and eat heartily. Their food gives them a comfortable 

 sensation, and they are well nourished. But the student, 

 the clerk, the 'watchmaker, the engraver, all men engaged 

 in sedentary employments, and men and women of no 

 occupation, often complain of failing appetite and weak 

 digestion. If they eat heartily, they feel now and then dis- 

 tressed after so doing, and give painful evidence that if a 

 man do not work, he cannot eat satisfactorily. The food the 

 inactive man eats gives him neither the nourishment, nor 

 the elastic energy, nor the pleasurable sensations, that it does 

 to the man of more active habits. 



655. So closely is use of the muscular system connected 

 with appetite and digestion, that exercise is usually one of 

 the first means advised for their restoration when they are 

 impaired ; and thus we see dyspeptic students leaving col- 

 lege, and dyspeptic sedentary men giving up their busi- 

 ness, and betaking themselves to travelling, to farming, or 

 some other active employment, as the best method of regain- 

 ing their lost health. But if the amount of exercise which 

 the invalid takes as a means of recovery had been distributed 

 through his previous days, and mingled with the hours of 

 study and sedentary occupation, very probably it would have 

 saved him from his present suffering and indigestion. 



656. When we run, or walk, or labor in any way, the 

 heart beats more rapidly than when we are at rest. The 

 blood is carried, not only more frequently, but in larger 

 quantities, through the muscular system, and through the 

 whole frame. The alternate swelling and decline of the 

 muscles, in their contraction and relaxation, press upon the 

 veins, and force the blood out of them; and, as the valves in 

 the veins do not permit this blood to go backward, it must 

 go onward toward the heart. This is especially seen in the 

 process of bleeding from the arm, when the patient holds a 

 cane or ball in his hand, upon which he presses and re- 

 laxes his fingers in rapid succession. This action swells the 

 muscles on the arm, the swelling presses upon the. veins, and 

 forces the blood onward and outward through the aperture. 



