1921] 



on Quality of Protein in Nutrition 



mono-amino acids. Gelatin lacks cystine, tyrosine, and tryptophan. 

 Hair is richest in cystine. These are simply some of the most 

 obvious differences. 



Our analytical data are far from complete ; in no case do the 

 totals of the amino acids add up to 100. The incompleteness is 

 chiefly due to the great difficulty of separating and estimating the 



Table I. 



individual amino acids. There may be still some unknown amino 

 acids in small quantities : hydroxyglutamic acid has been discovered 

 recently by Dakin by a new extraction method. This method may 

 yet lead to new results ; once again it has proved that every new 

 process in connection with the chemistry of the proteins has given 

 a valuable result. 



Rather too great stress has been laid upon the analytical figures. 



