6 VOELCKER on the Chemistry of Food. 



described as protein compounds. The discoverer of protein 

 (Professor Mulder) was the first to suggest this name, as he 

 regards albumen and the other albuminous substances as com- 

 pounds of protein, with small and variable quantities of sulphur 

 or phosphorus, or both. Not only are these substances nearly 

 identical in composition and properties with each other, but they 

 resemble so intimately animal albumen, casein and fibrin, or 

 those materials of which the flesh and blood of animals prin- 

 cipally consist, that they have been called with much propriety 

 flesh or muscle forming principles. Oilcake, peas and beans, 

 and other leguminous seeds, are very rich in flesh-forming prin- 

 ciples ; oats, barley, and wheat, likewise contain a considerable 

 proportion of these substances. In smaller quantities they occur 

 in roots, grass, hay, and all other kinds of feeding-stuffs. On 

 the whole, however, the plants which serve as food to animals 

 are, comparatively speaking, poor in albuminous compounds, but 

 rich in starch or gum, sugar, cellular and woody fibre, or any 

 other non-nitrogenized substance. Plants thus present the 

 animal with a mixture in which the substance of the muscle, so 

 to speak, exists ready-formed; for without undergoing great 

 changes in the stomach of the animals, the albuminous com- 

 pounds are readily assimilated and converted into blood and 

 muscular fibre. 



No food entirely destitute of flesh-forming constituents is 

 capable of supporting animal life for any length of time : hence 

 the great importance which is attached to these compounds by 

 the physiologist. Many careful experiments have proved nearly 

 beyond dispute the fact that the animal organism does not possess 

 the power inherent in plants, of compounding and preparing the 

 substance of the muscles from its elements ; unless, therefore, food 

 is presented to animals which contains ready-made muscle, they 

 soon become emaciated and rapidly perish. 



Thus it has been shown that dogs fed upon arrowroot, sugar, 

 gum, butter, and other food, entirely destitute of flesh-forming 

 principles, rapidly lose all flesh and die at the end of the fifth 

 or sixth week, or a little later than they would if no food of any 

 description were given. Similar experiments have been tried with 

 sheep and geese. Thus Macaire and Marcet fed a sheep weighing 

 53 Ibs. with food perfectly free from nitrogen. On the 20th day 

 after the beginning of the experiment death occurred, and the 

 weight of the sheep was found reduced to 31 Ibs. 



Tiedeman and Gmelin obtained similar results with geese : a 

 goose weighing 6 Ibs. 1 oz. was fed with sugar, and died on the 

 22nd day after the experiment had begun, and then weighed only 

 4 Ibs. 8 oz. Another goose weighing 87 Ibs. was fed with 



