NUTRITIVE VALUES. 47 



Krummacher, a carrying the work begun by Kirchmann still 

 further, found that when the entire energy requirement of the dog 

 was covered by gelatin the total sparing was only 37.5 per cent of 

 the fasting nitrogen. Applied to a man whose energy requirement 

 is 2,500 calories daily Krummacher calculates that if 5 per cent of 

 his requirements were supplied in gelatin (i. e. about 33 grains of dried 

 and purified gelatin), the proteid' destruction in his body would be 

 reduced from 70 grams to about 56 grams, or, in other words, the 33 

 grams of gelatin would replace 14 grams of proteid. 



Gregor 6 used gelatin in feeding infants in certain cases where 

 excess of proteid was contraindicated, and concluded that with a diet 

 containing 4.8 grams of nitrogen per day (of which "nearly all" was 

 gelatin N), not more than half as much nitrogen was lost from the body 

 as in starvation. 



Brat c prepared a gelatose, which he identifies by 'Chittenden's d 

 method as a deuterogelatose, and fed it to convalescent patients as a 

 substitute for a portion of the proteid in their diets. 



Mancini 6 studied the nitrogen balance of five convalescents from 

 typhoid fever, while giving " large quantities" of gelatin. He 

 observes a considerable retention of nitrogen, but doubts whether 

 proteid nitrogen can be replaced by gelatin nitrogen. 



Kauffmann / studied the replacing power of gelatin in a diet con- 

 taining "only as much proteid (mainly casein) as is necessary with a 

 sufficient supply of energy for maintenance of the body's condition." 

 He concludes from his experiments on dogs that not more than one- 

 fifth of the proteid in such a diet can be replaced by (pure) gelatin 

 if nitrogen equilibrium is to be maintained. With one-fourth of the 

 proteid nitrogen so replaced a small minus balance occurs. Kauff- 

 mann's paper is concerned chiefly with the attempt to bring gelatin 

 up to the full nutritive value of proteid by adding to it the amido- 

 acids which it lacks, but which casein contains. 



Rona and Muller,^ in attempting to confirm Kauffmann's results 

 with gelatin, tyrosin, and tryptophan, found first "the smallest 

 quantity of proteid nitrogen with which the animal could well get 

 along," and then replaced one-fifth of this proteid (casein) with 

 gelatin nitrogen. Their observation as regards the amount which 

 would be replaced was quite in accord with Kauffmann's, for when 

 gelatin was substituted for two-fifths of the casein there was a dis- 

 tinct minus balance. 



oZts. Biol., 1901, 42:242. 



& Centralblatt fur innere Medicin, 1901, 22 : 65. 



c Deutsche medicinische Wochenschrift, 1902, p. 21. 



rfj. Physiol., 1891, 12:23. 



eReale Accademie dei Fisiocritici di Sieni, 1905, 17:667. 



/Archiv gesam. Physiol., 1905, 109:440. 



9Zts. physiol. Chem., 1907, 50:263. 



