NECESSARY QUANTITY AND VARIETY OF FOOD 155 



preparation of coffee, which may account for its more marked effects on 

 the system. 



Chocolate. Chocolate is made from the seeds of the cocoa-tree, 

 roasted, deprived of their husks and ground with warm rollers into a 

 pasty mass with sugar, flavoring substances being sometimes added. 

 It is then made into cakes, cut into small pieces or scraped to a powder, 

 and boiled with milk or milk and water, when it forms a thick, gruel- 

 like drink, which is highly nutritive and has some of the exhilarating 

 properties of coffee or tea. Beside containing a large proportion of 

 nitrogenous matter resembling albumin, the cocoa-seed is rich in fatty 

 matter and contains a peculiar substance, theobromin (C 7 H 8 N 4 O 2 ), analo- 

 gous to caffein and thein, which is supposed to possess similar physio- 

 logical properties. 



Condiments and Flavoring Articles. The refinements of cookery 

 involve the use of many articles that can not be classed as alimentary 

 substances. Pepper, capsicum, vinegar, mustard, spices and other 

 articles of this class, so commonly used, have no decided influence on 

 nutrition, except in so far as they promote the secretion of the digestive 

 juices. Common salt, however, is very important, and this has been 

 considered in connection with inorganic alimentary substances. The 

 various flavoring seeds and leaves, truffles, mushrooms etc. have no 

 physiological importance except as they render articles of food more 

 palatable. 



Quantity and Variety of Food necessary to Nutrition. The inferior 

 animals, especially those not subjected to the influence of man, regu- 

 late by instinct the quantity and kind of food. The same is true of 

 man during the earliest periods of his existence ; but later in life, the diet 

 is variously modified by taste, habit, climate and what may be termed 

 artificial wants. It is usually a safe rule to follow the appetite in re- 

 gard to quantity, and the tastes, when they are not manifestly vitiated 

 or morbid, in regard to variety. The cravings of nature indicate when 

 to change the form in which nutriment is taken ; and that a sufficient 

 quantity has been taken is manifested by a sense, not exactly of satiety, 

 but of evident satisfaction of the demands of the system. During early 

 life, the supply must be a little in excess of the actual loss, in order to 

 furnish materials for growth ; during the later periods, the quantity of 

 nitrogenous matter assimilated is somewhat less than the loss ; but in 

 adult age, the system is maintained at a tolerably definite standard by 

 the assimilation of matter about equal in quantity to that discharged in 

 the form of excretions. 



Although the loss of substance by katabolism creates and regulates 

 the demand for food, it is an important fact, never to be lost sight of, 



