UTAH ACADEMY OF SCIENCES 105 
RECENT ADVANCES IN OUR KNOWLEDGE OF 
PROTEIN METABOLISM. 
By H. A. MATTILL. 
(Abstract). 
The experiments of Osborne and Mendel on Feeding 
with Isolated Proteins, and those of Abderhalden and his 
co-workers have emphasized the importance of the individ- 
ual proteins and their decomposition products as the units 
of protein nutrition. The specificity of the proteins of ani- 
mal and plant origin necessitates their complete decomposi- 
tion into these units, the various amino acids, when they 
are to be used as food by another animal. The synthesis 
of the new protein from these decomposition products takes 
place not in the intestinal mucosa during absorption, as 
has been held, heretofore, because of absence of positive 
evidence, but in the tissues of the body generally, under the 
direct and immediate control of the individual cells. The 
synthetic power of the animal cell has been greatly under- 
estimated. Evidence for this cellular synthesis has been 
obtained in the Harvard laboratories with the help of a 
new and accurate method for determining non-protein ni- 
trogen in blood and tissues. A clinical application of this 
method promises to be of great value in determining the 
functional activity of the kidney. 
