THE PROTEINS OF COW’S MILK.* 
' By THOMAS B. OSBORNE anp ALFRED J. WAKEMAN. 
WITH THE COOPERATION OF CHARLES S. LEAVENWORTH AND 
Owen L. Nowan. 
(From the Laboratory of the Connecticut Agricultural Experiment Station, 
New Haven.) 
(Received for publication, November 22, 1917.) 
Although casein has been the subject of numerous investiga- 
tions during the past few years, very little attention has been 
given to the other proteins of milk, notwithstanding the fact 
that the published data regarding these are comparatively 
meager. The reason for this is doubtless based on the idea, 
which formerly seems to have been held generally, that since 
casein forms about 80 per cent of the total protein in milk, the 
other proteins have such a.subordinate importance in nutrition 
that a special investigation of them is not important. 
Since recent studies of the chemical constitution, as well as 
of the relative nutritive value of individual proteins, have shown 
such wide differences between several of them, and especially 
since the heat-coagulable protein of milk, the so called lactalbu- 
min, has appeared to be preeminently adapted to the nutritional 
requirements of growing animals, it has seemed worth while to 
learn more than is now known respecting these proteins. This 
has furthermore become important in view of the now generally 
recognized fact that milk contains among its water-soluble con- 
stituents the so called vitamines, which are essential for the 
growth of young, as well as for the continued maintenance of 
adult animals. : 
In all attempts to discover the nature of the water-soluble 
vitamine in milk it is essential to know the properties and pro- 
* The expenses of this investigation were shared by the Connecticut 
Agricultural Experiment Station and the.Carnegie Institution of Wash- 
ington, D. C. 
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