282 MAINE STATE COLLEGE 



THE COEFFICIENTS OF DIGESTIBILITY FOE PROTEIN. 



W. H. Jordan and L. H. Merrill. 



The reports of this Station for 1886-7, pp. 127 to 135, and 1888, 

 pp. 195-203, contain the results of an attempt to study the error 

 involved in the usual method of determining the digestibility of 

 protein. Several facts were very clearly shown, which are in part 

 only a confirmation of the results previously obtained by German 

 investigators. The data in the reports referred to show; (1st) 

 that the coefficients of digestibility for protein as ordinarily 

 determined are very much smaller than those obtained by pepsin- 

 pancreas digestion ; (2nd) that in the cases tested from fourteen 

 to thirty-five per cent, of the fsecal nitrogen was soluble under 

 conditions that presumably would cause no extraction of albumi- 

 noid compounds ; (3rd) that the average coefficients of digesti- 

 bility as determined by the use of artificial pepsin and pancreas 

 solutions are practically the same as those obtained when allow- 

 ance is made for the fsecal nitrogen soluble in ether, alcohol, hot 

 water and limewater. A study of this question has been con- 

 tinued in connection with the digestion trials which are previously 

 described in this report, and with results almost identical with those 

 formerly obtained. 



Of the three methods tried in 1888, for the separation of the 

 biliary and other waste products of the fasces, only one was used 

 in connection with the work here reported, namely ; method B, 

 which consists in the extraction of the faeces with ether, the same 

 as for the fat extraction, followed by successive extractions with 

 hot alcohol and hot water for about ten minutes each, this treat- 

 ment being followed by extraction with lime water, which consists 

 in letting one gram of the substance stand in a cold, saturated solu- 

 tion of lime water for six hours. Tlie following table shows the 

 percentage of nitrogen that was dissolved by this treatment : 



