FOOD. 117 



long nutritious, unless a certain proportion of these substances be 

 present in it. Since they are so abundant as ingredients of the body, 

 their absence from the food is felt more speedily than that of any other 

 substance except water. They have, therefore, sometimes received the 

 name of " nutritious substances," in contradistinction to those of the 

 second class, which contain no nitrogen, and which are found to be 

 insufficient for the support of life. The albuminous substances, however, 

 when taken alone, are no more capable of supporting life indefinitely 

 than the others. It was found in the experiments of the French 

 " Gelatine Commission" 1 that animals fed on pure fibrine and albumen, 

 as well as those fed on gelatine, become, after a short time, much 

 enfeebled, refuse the food offered to them, or take it with reluctance, 

 and finally die of inanition. This result has been explained by sup- 

 posing that these substances, when taken alone, excite after a time 

 such disgust that they are either no longer taken, or if taken are not 

 digested. But this disgust is simply an indication that the substances 

 used are insufficient and finally useless as articles of food, and that the 

 system demands other materials for its nourishment. It is well de- 

 scribed by Magendie, in the report of the commission above alluded 

 to, while detailing his investigations on the nutritive qualities of gela- 

 tine. " The result," he says, " of these first trials was that pure gelatine 

 was not to the taste of the dogs experimented on. Some of them suf- 

 fered the pangs of hunger with the gelatine within their reach, and would 

 not touch it ; others tasted of it, but would not eat ; others still de- 

 voured a certain quantity once or twice, and then obstinately refused to 

 make any further use of it." 



In one instance, Magendie succeeded in inducing a dog to take a 

 considerable quantity of pure fibrine daily throughout the whole course 

 of the experiment ; but notwithstanding this, the animal became ema- 

 ciated, and died at last with the symptoms of inanition. 



It is evident, therefore, that no single proximate principle, nor even 

 any one class alone, can be sufficient for nutrition. The albuminous 

 substances are first in importance because they constitute the largest 

 part of the mass of the body ; and exhaustion follows more rapidly 

 when they are withheld than when the animal is deprived of other kinds 

 of alimentary matter. But starchy and oleaginous substances are also 

 requisite ; and the body feels the want of them sooner or later, though 

 it may be plentifully supplied with albuminous food. Finally, the inor- 

 ganic saline matters, though in smaller quantity, are also necessary to 

 the continued maintenance of life. In order that the animal tissues and 

 fluids remain healthy, and take their proper part in the functions of 

 life, they must be supplied with all the ingredients necessary to their 

 constitution ; and a man may be starved to death at last by depriving 

 him of sodium chloride or lime phosphate as surely, though not so 

 rapidly, as if he were deprived of albumen or oil. 



1 Comptes Rendus de l'Acad6mie des Sciences. Paris, 1841, torn. xiii. p. 267. 



