106 OF FOOD. 



were supplied with water alone they lived six, eight, and even ten 

 days longer than if they were deprived at the same time of both 

 solid and liquid food. Chloride of sodium, also, is usually added 

 to the food in considerable quantity, and requires to be supplied 

 with tolerable regularity ; but the remaining inorganic materials, 

 such as calcareous salts, the alkaline phosphates, &c., occur natu- 

 rally in sufficient quantity in most of the articles which are used as 

 food. 



The proximate principles of the second class, so far as they con- 

 stitute ingredients of the food, are naturally divided into two 

 groups : 1st, the sugar, and 2d, the oily matters. Since starch is 

 always converted into sugar in the process of digestion, it may be 

 included, as an alimentary substance, in. the same group with the 

 sugars. There is a natural desire in the human species for both 

 saccharine and oleaginous food. In the purely carnivorous animals, 

 however, though no starch or sugar be taken, yet the body is main- 

 tained in a healthy condition. It has been supposed, therefore, that 

 saccharine matters could not be absolutely necessary as food ; the 

 more so since it has been found, by the experiments of Cl. Bernard, 

 that, in carnivorous animals kept exclusively on a diet of flesh, 

 sugar is still formed in the liver, as well as in the mammary gland. 

 The above conclusion, however, which has been drawn from these 

 facts, does not apply practically to the human species. The car- 

 nivorous animals have no desire for vegetable food, while in the 

 human species there is a natural craving for it, which is almost 

 universal. It may be dispensed with for a few days, but not with 

 impunity for any great length of time. The experiment has often 

 enough been tried, in the treatment of diabetes, of confining the 

 patient to a strictly animal diet. It has been invariably found that, 

 if this regimen be continued for some weeks, the desire for vegetable 

 food on the part of the patient becomes so imperative that the plan 

 of treatment is unavoidably abandoned. 



A similar question has also arisen with regard to the oleaginous 

 matters. Are these substances indispensable as ingredients of the 

 food, or may they be replaced by other proximate principles, such 

 as starch or sugar ? It has already been seen, from the experiments 

 of Boussingault and others, that a certain amount of fat is produced 

 in the body over and above that which is taken with the food ; and 

 it appears also that a regimen abounding in saccharine substances 

 is favorable to the production of fat. It is altogether probable, 

 therefore, that the materials for the production of fat may be 



