122 HUMAN PHYSIOLOGY 



is most suitable. Animal food is not suitable as an exclusive 

 diet because it contains no carbohydrates ; on the other 

 hand, the vegetables contain too little proteid and no fat. 

 Also the structure of the digestive organs of man indicates 

 that he is intermediate between the exclusive carnivorous 

 and herbivorous animals. In flesh-eating animals the length 

 of the intestine is about five times that of the body (reckoned 

 from mouth to anus), in the plant-eaters it is more than 

 twenty times this length. The great length of the intestine 

 of herbivorous animals serves to offset the more rapid move- 

 ment of the food, in order that the food may be sufficiently 

 acted upon and absorbed. As the length of the intestine of 

 man is about ten times that of his body, he is intermediate 

 between the carnivorous and herbivorous animals. 



As can be observed in vegetarians, man can indeed be nourished 

 by vegetable foods only, but there are no sufficient reasons for 

 excluding meat altogether from our diet. An exclusive meat diet 

 cannot be endured by man for any great length of time because 

 of the resulting disturbance in digestion. 



As many of the foods supplied us by nature are odorless and 

 tasteless, we spice them. The physiological significance of spices 

 lies in the fact that they increase the secretion of the digestive 

 juices, thereby aiding digestion and stimulating the appetite. 



Of the various drinks, which are chiefly spices (coffee, tea, 

 cocoa, alcoholic drinks), cocoa may also be considered as a food, 

 because it contains much proteid (12$), carbohydrates (13$), and 

 fat (in cocoa not freed of its fat, 49$). Beer also contains food- 

 stuffs (proteid up to o.8#, carbohydrates 5-6^). but it can never- 

 theless not be classified as a food, for. taken in large quantities, 

 the harmful effects of alcohol are manifested. Besides this, the 

 cost of beer is much too high in proportion to its food value. 



Certain sensations hunger and thirst may be regarded 

 as the stimulations for taking up food and drink. (See 

 Chapter XXVI.) 



