122 ALIMENTATION. 



this is not so delicate in flavor as chocolate. A brown mu- 

 cilaginous infusion is sometimes made of the husks (shells). 

 This has a slight chocolate-flavor, but does not possess the 

 nutrient properties of the kernels. 



Quantity and Variety of Food necessary to Nutrition. 



The inferior animals, especially those not subjected to the 

 influence of man, regulate by instinct the quantity and kind 

 of food which they consume. The same is true of man dur- 

 ing 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 with regard to quantity, and the tastes 

 when they are not manifestly vitiated or morbid with regard 

 to variety. The cravings of nature indicate when to change 

 the form in which nourishment 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 the first periods of life, the supply must be 

 a little in excess of the actual loss in order to furnish mate- 

 rials for growth. During the latter periods, the quantity of 

 nitrogenized matter assimilated is somewhat less than the 

 loss ; but in adult age, the system is maintained at a tolera- 

 bly definite standard by the assimilation of material about 

 equal in quantity to that which is discharged in the form of 

 excretions. 



Although the loss of substance by destructive assimilation 

 creates and regulates the demand for food, it is an important 

 fact, never to be lost sight of, that the supply of food has a 

 very great influence upon the quantity of the excretions. 

 As an illustration of this, we may take the influence of food 

 upon the exhalation of carbonic acid ; l and this is but an 

 example of what takes place with regard to the other excre- 

 tions. The quantity of the excretions is even more strikingly 

 modified by exercise, which, within physiological limits, in- 



1 See vol. i., Respiration, p. 435 e*. seq. 



