548 DIGESTION. 



phosphorus, and contains more nitrogen or less carbon than protein* 

 The compounds of protein, under the influence of the vital energy of 

 the organs that form the blood, assume a new form, but are not altered 

 in composition ; whilst these organs, as far as our experience reaches^ 

 do riot possess the power of producing compounds of protein, by virtue 

 of any influence, from substances that contain no protein. Animals, 

 which were fed exclusively on gelatin, the most highly nitrogenized ele- 

 ment of the food of carnivora, died with symptoms of starvation." "In 

 short," he adds, "gelatinous tissues are incapable of conversion into 

 blood." Such too, seems to be the opinion of Professor Be'rard. 1 Yet 

 it has been shown above, that fibrin and albumen both compounds of 

 protein when exhibited singly to animals, nourished them as imper- 

 fectly as gelatin; and there is some reason to believe, that it is mainly 

 on chemical considerations that the value of gelatin as a nutriment 

 has been much underrated. " Such persons only/' says Professor 

 Mulder, 2 "as are under the influence of prejudice (making their experi- 

 ments with dogs animals which, according to the account of the gela- 

 tin committee, prefer to starve in the midst of gelatin, rather than 

 touch it), such persons only as deny the results of innumerable ob- 

 servations, will refuse to gelatin its place among useful nutritive sub- 

 stances." And he adds: "I have thought it necessary, before closing 

 this short account of gelatin, to express my opinion of the experiments 

 by which pure gelatin is rejected as food: namely, that these experi- 

 ments have taught me nothing but how experiments ought not to be 

 made." It is somewhat singular, too, that most of those who deny 

 much nutrient property to gelatin are of opinion, that the nutritious 

 properties of different articles of vegetable food may be generally esti- 

 mated by the proportion of nitrogen they contain, and on this principle 

 tables have been formed by several experienced chemists, by Boussin- 

 gault, Schlossberger, Kemp, 3 and Professor Horsford, 4 of Cambridge, 

 Massachusetts. The latter gentleman, especially, has furnished us 

 with the results of elaborate investigations into the nature of different 

 kinds of vegetable food, based upon the amount of nitrogen. The 

 tables of Boussingault and Horsford are considered by Professor Fre- 

 richs, 5 of value; whilst those of Schlossberger and Kemp are declared 

 to be practically useless, because no regard was paid to the quantity 

 of water in the fresh condition; and for the strange reason, "that the 

 nitrogen found in most of the substances analyzed that contain gelatin 

 is no measure of the quantity of the hsematogenetics or blood-forming 

 constituents!" 



Independently of showing the necessity of variety of food for animal 

 sustenance, the experiments of M. Magendie exhibit some singular 

 anomalies ; and sufficiently demonstrate, that we have yet much to learn 



1 Archives Generates de Medecine, Fevrier, 1850, p. 247. 



2 The Chemistry of Vegetable and Animal Physiology, by G. J. Mulder, &c., p. 328, 

 Edinb. and Lond., 1849. 



3 Annal. der Chemie und Pharmacie, B. Ivi. s. 78-94 ; see also, Philosophical Magazine 

 for Nov., 1845. 



4 Philosophical Magazine, for Nov., 1846, p. 365. 



5 Art. Verdauung, in Wagner's Handworterbuch der Physiologic, 19te Lieferung, s. 732, 

 Braunschweig, 1848. 



I 



