334 APPENDIX. 



few persons know how rightly to appreciate considerable and 

 constant exercise in the open air as a medical agent and 

 preserver of health. But it is probable, that the same vital 

 energies, which are concerned in all the movements of 

 muscular activity, and of thought, and which customary 

 language has ascribed to the brain and nervous system, are 

 engaged after taking our food in the work of digestion. And 

 it has been found, conformably to this notion, that exertion 

 after meals has interrupted the chylopoietic processes, and has 

 caused unpleasant feelings in the stomach, and subsequent 

 weakness. Great mental exertions, or anxiety, have had the 

 same effect. The gentle stimulus of company after dinner, 

 may, perhaps, be beneficial, by assisting to produce those 

 nervous energies, which hard exercise might dissipate among 

 the muscles at a time when they ought to be spent on the 

 stomach, that that organ might pour out sufficient of the 

 gastric juice to convert the alimentary matter into chyle, 

 and subsequently on the liver, pancreas, and secretory coats 

 of the intestines ; that by the after aid of their proper fluids, 

 the chyle may be properly formed for absorption and nutri- 

 ment. Exercise, while these processes are going on, may be 

 regarded as an interruption to them : though, if used several 

 hours after eating, it appears often to assist the peristaltic 

 action of the intestines. 



The food is the next subject of consideration. It has been 

 often said, that, in a natural state, the quantity and quality 

 of our food would be regulated by desire and opportunity : 

 but as we know little about man in a natural state, we must 

 regulate our diet by the experience of what is best in a state 

 of artificial society. Physiologists have laid great stress on 

 proportioning the quantity of food to the power of the 

 stomach ; and it is rational to consider, that what is not 



