n6 ELEMENTARY BIOLOGY 



It is impossible to lay down rules as to the number or regu- 

 larity of meals. This is something that each one has to settle 

 for himself on the basis of experience. It is probably advan- 

 tageous to adopt regular hours for meals, and to avoid, so far 

 as possible, interfering with this program either by changing 

 the hours or by eating between meals. 



In making a program that will leave a fixed time for each 

 meal, we must consider the other things that are being done 

 during the day. It is well to avoid hard work of any kind 

 immediately after meals. Exertion of the muscles causes an 

 increase of blood-flow to those muscles and a corresponding 

 decrease in the blood-flow to the digestive system. As a result, 

 the secretion of digestive juices is reduced, and the process of 

 digestion is slowed down. The food remains in the stomach 

 a very long time, overworking the muscles of that organ, some- 

 times to the point of actual distress. Effects of the same kind 

 are produced whether the work done is in the nature of pro- 

 ductive labor or merely free play. Similar consequences are 

 found to arise from bathing too soon after a meal ; in this case 

 the flow of blood is to the skin, but the effect on the stomach 

 is the same. 



150. Health habits. We have seen that we have no direct 

 control over the workings of the digestive system ; we must 

 therefore establish habits at the few points where we have 

 indirect control. The first point has to do with eating, and the 

 establishment of suitable eating habits should be our first con- 

 sideration. The second point at which we have control of the 

 digestive system is in the establishment of habits related to the 

 behavior of the large intestine. And, finally, there are certain 

 general habits of exercise and breathing and sleeping, which, on 

 the one hand, are largely under our control, and which, on the 

 other hand, have an influence on the digestive system. 



We may summarize the habits that are of importance to us 

 in this connection ; for most of them the reasons have already 

 appeared in the preceding discussion. 



