222 HAND-BOOK OF PHYSIOLOGY. 



III. EFFECT OF TOO MUCH FOOD. 



Sometimes the excess of food is so great that it passes through the ali- 

 mentary canal, and is at once got rid of by increased peristaltic action of 

 the intestines. In other cases, the unabsorbed portions undergo putre- 

 factive changes in the intestines, which are accompanied by the produc- 

 tion of gases, such as carbonic acid, carburetted and sulphuretted hydro- 

 gen; a distended condition of the bowels, accompanied by symptoms of 

 indigestion, is the result. An excess of the substances required as food may, 

 however, undergo absorption. It is a well-known fact that numbers of 

 people habitually eat too much; especially of nitrogenous food. Dogs 

 can digest an immense amount of meat if fed often, and the amount of 

 meat taken by some men would supply not only tihe nitrogen, but the 

 carbon which is requisite for an ordinary natural diet. A method of get- 

 ting rid of an excess of nitrogen is provided by the digestive processes in 

 the duodenum, to be presently described, whereby the excess of the albu- 

 minous food is capable of being changed before absorption into nitroge- 

 nous crystalline matters, easily converted by the liver into urea, and so easily 

 excreted by the kidneys, affording one variety of what is called luxus 

 consumption; but after a time the organs, especially the liver, will yield 

 to the strain of the over- work, and will not reduce the excess of nitroge- 

 nous material into urea, but into other less oxidized products, such as uric 

 acid; and general plethora and gout may be the result. This state of 

 things, however, is delayed for a long time, if not altogether obviated, 

 when large meat-eaters take a considerable amount of exercise. 



Excess of carbohydrate food produces an accumulation of fat, which 

 may not only be an inconvenience by causing obesity, but may interfere 

 with the proper nutrition of muscles, causing a feebleness of the action 

 of the heart, and other troubles. The accumulation of fat is due to the 

 excess of carbohydrate being stored up by the protoplasm in the form of 

 fat. Starches when taken in great excess are almost certain to give rise in 

 addition to dyspepsia, with acidity and flatulence. There is a limit to 

 the absorption of starch and of fat, as, if taken beyond a certain amount, 

 they appear unchanged in the faeces. 



Requisites of a Normal Diet. It will have been understood that 

 it is necessary that a normal diet should be made up of various articles, 

 that they should be well cooked, and should contain about the same 

 amount of the carbon and nitrogen that are got rid of by the excreta. 

 Without doubt these desiderata may be satisfied in numerous ways, and 

 it would be simply absurd to believe that the diet of every adult should 

 be exactly similar. The age, sex, strength, and circumstances of each 

 individual should ultimately determine his diet. A dinner of bread and 

 hard cheese with an onion contain all the requisites for a meal; but such 



