April ii, 1890.] 



SCIENCE. 



229 



Various standards for daily dietaries for a man doing a 

 moderate amount of work have been proposed by various 

 authors, and the reader interested in such matters is referred 

 to the last (third) edition of Dr. I. Konig's " Zusammenset- 

 zung der mensch lichen Nahrungs und Genussmittel " (Ber- 

 lin, 1889) for much information on the subject. 



Below will be found a table,' prepared by Professor C. A. 

 Meinert, giving the composition (in grams^) of the daily ra- 

 tions of the different European armies: — 



representing the undigested materials, and the difference 

 the amount digested. No trouble is found in feeding an ox 

 or a horse on a diet of hay and water for a long period ; but 

 when a human being is taken for experiment, no matter how 

 simple or palatable the food-material may be, it very soon 

 becomes repugnant to him, the digestive functions are dis- 

 turbed, and the accuracy of the experiment impaired. Ibis 

 is especially true where a diet of fat is tried. 



Instead of the living subject, resort lias been made to arti- 



W '- Z > E 



B,- s" 



0. p.i -p 



Digestibility of Foods. 



The digestibility of foods is an important part of this sub- 

 ject, and it is to German chemists that we owe the greater 

 part of our knowledge. The number of reliable investiga- 

 tions and experiments is very small, about sixty altogether, 

 and the results obtained are tabulated in Table V. 



Experiments in the digestibility of different cattle-foous 

 have long been a subject of investigation by the different 

 agricultural experiment stations in Europe, and the data ob- 

 tained have been made use of in various ways, e.g., in 

 quickly fattening cattle for the market. 



The general method pursued consists in analyzing and 

 weighing both the food consumed and the excreta; the latter 



' From Konig's Chemie der meuschliohen Nahrungs- und Qenussmittel 

 (Berlin, 1,S89), p. 156. 



^ One gram equals 15 4 Troy grains ; one ounce avoirdupois equals 28.35 

 grams. 



ficial digestion, when the food-material has been placed in a 

 suitable vessel with a solution containing pepsin, and sub- 

 jected, with occasional agitation, to the action of heat, at 

 body temperature, for twenty-four hours, portions being 

 taken out at different intervals and subjected to microscop- 

 ical and chemical examination. 



From experiments made by Herr Jensen' in the labora- 

 tory of the University of Tubingen, it appears that raw meat 

 is much sooner digested than cooked meat. The raw beef 

 was digested in two hours; the boiled, '"half done," was di- 

 gested iri two and a half hours; the boiled, "well done," 

 was digested in three hours; the roasted, "half done," was 

 digested in three hours; the roasted, "well done," was di- 

 gested in four hours. 



In regard to the relative digestibility of butter and oleo- 

 margarine, the only actual comparative tests on record are 



1 Century, xxxlv. p. 739. 



