238 FORMATION OF FAT. 



rich in the elements of respiration. It happens, 

 however, that the food of animals, for the most part, 

 is rich in both forms of nutriment. 



613. A large accumulation of fat in an animal can 

 never be considered as healthy ; but, on the other 

 hand, leanness or the absence of fat is also unhealthy, 

 because, if at any time exposed to cold, hunger, or 

 violent exercise, the tissues of the body itself will be 

 consumed and converted into elements of respiration, 

 whilst in an animal supplied with a reasonable pro- 

 portion of fat, the latter will be consumed first, before 

 the tissues of the body will be thus acted on. 



614. Some animals fatten far more easily than 

 others do ; this depends partly on their general con- 

 struction, and partly on the circumstances to which 

 they are exposed — such as temperature, abundance 

 and kind of food, exercise, &c. In man, too, the 

 greater or less activity of the mind exerts a very 

 remarkable influence on all the functions of the body; 

 and, therefore, amongst others, on the formation of 

 fat. 



615. Setting aside individual peculiarities of con- 

 struction, the size of the lungs, &c., the circumstances 

 most favorable to the formation and secretion of fat, 

 are warmth, little exercise, abundance of food, and 

 the absence of all worry and irritation. Under these 

 circumstances, an animal is supplied with as much of 

 the elements of flesh as sufiices to keep up the healthy 

 state of all the tissues of the body ; having an excess 

 of the elements of respiration, there is a natural 



