532 APPLIED BIOLOGY 



It is argued that stimulants are not natural, for animals do 

 not require such things ; but it may be answered that ani- 

 mals do not lead sedentary lives, undergo intense nervous 

 strain, and do similar things which in civilized man tend to 

 interfere with proper digestion. Certainly we can often gain 

 by the temperate use of some stimulants; but harm will 

 always come from overstimulation, which is most likely to 

 happen in the use of tea and coffee ( 480) and alcohol ( 468). 

 Probably the most useful and safest of all stimulants are 

 hot foods and hot drinks, such as hot bouillon, hot milk, or 

 even hot water. 



456. Psychology of Digestion. We have already defined 

 psychology as the science of the mind ; and here it is impor- 

 tant to note that the mind greatly influences digestion. It is 

 well known that the thought, sight, or smell of savory food 

 causes the " mouth to water," that is, stimulates the salivary 

 glands; and there is a similar effect on the gastric glands. 

 We also know how certain disagreeable mental states may 

 cause loss of appetite and even nausea. In fact, the gastric 

 glands may fail to secrete, and indigestion and other dis- 

 turbances may be caused by the direct influence of the 

 mind. 



Such well-known facts suggest the importance of pleasant 

 surroundings while one is eating. Here is the secret of the 

 good digestive influence of music, jolly company, and other 

 things which make for a happy state of mind during the meal 

 hour. That is a time when every one should drop his cares 

 and troubles. 



On the other hand, there is a certain real danger in pleas- 

 ant accompaniments of meals. It is simply that fine fare 

 and surroundings which are agreeable to all the senses tend to 

 feasting or overeating, a result often capable of unhealthful 

 consequences. The only safety is in learning self-control so 

 that one's stimulated appetite may not lead on and on to 

 gluttony. 



