APPETITE OP SWINE 
381 
ing. organism”. Osborne^® and Mendel have done classic re- 
search along these ■ lines, as have AhderhaldeiP" and others. 
Proteins, being built up of some eighteen or more amino-acids 
or building stones, offer a very complicated subject for specific 
study. 
When it is realized fully that these eighteen amino-acids in 
their various possible combinations- can form millions upon mil- 
lions of proteins, no two of which are alike, we stand astounded. 
The great possibilities of combination and recombination that 
are evident make one rather pause before the stupendous prob- 
lems involved in the assimilation and functioning of proteins of 
the many sorts.' The appetite of the pig possibly may fairly 
quickly tell us more about which of these amino-acids should be 
present in his ration and in what amount much more effectively 
than long, laborious, standard, ordinary chemical and physio- 
logical research. At any rate, the indications are that the pig 
can come nearer selecting his protein diet naturally, than can 
technically trained men. 
Peculiarly enough, the pig shows great preference for milk, 
and for meat, the amino-acids of which are quite efficient. Is 
this a reason why growing pigs take to the milk and the meat so 
readily, and why after they are quite well- grown they may al- 
most cease eating the meat in the presence of the Indian corn or 
maize ? 
The carbohydrates, which in general chemical work are desig- 
nated as the Nitrogen-Free Extract plus Crude Fibre, are in 
reality a very intricate mixture of various compounds, in many 
and diverse proportions. There are lactose, the milk sugar, the 
starches, dextrins, sucrose, maltose, glucose, cellulose, the pento- 
sans, and a multitude of others. The mono- and poly- saccha- 
rides appear in various quantities and proportions. In view ot 
the very great development in protein physiological research the 
^‘’Osborne, Thomas E., and Mendel, Lafayette B. ; Feeding' ICxpeT imer.ts 
With Isolated Food Substances, Carnegie Institution of Washington, 1911, 
Pub. 156; Feeding Experiments Relative to the Nutritive VVi'-" of 
Jour. Biol. Chem., 1919, XIV;. Am. Jour. Physiol, 1913, (al '"NNt. 16; N-.- 
tritWe Properties of Proteins of - the Maize Kernel, Jour. Bi d. Cheiu.. 191*. 
(b) XVII, I; The Comparative Nutidtive Value of Certam Proteins in 
Growth, and the Problem of the Protein Minimum, Jnnr. Biol. Che-n.,' Ig''. 
XX. Osborne, Thomas B. ; The Nutritive Valpe of the Proteins of IMaize. 
Science, 1913, XXXVII. 1S5. .(These papers give furtiier references to the 
literature of the sub.iect.) ' 
vAbderhalden, E. ; Fiitterungsverruche mit vnllstii.ndi.g ahgehauten Nah’-- 
ungsstoffen, Ztschr. f. physiol. Chem.. -1912, liXXVII. 22. Ahderh.'i.lde.n, E., 
and T-Iirsch, P. : Flitterungsversuche n^it Gelatine, Ammonsalzen, volietandig 
ab,gebauten Eleisch und einen aus e.ilon bekannten Aminosn.uren hcrdiehenden 
Gemisch ansgeftihrt an jungen ITunden, Ztschr. f. physiol. Chem., 1912, 
LXXXI, 323. 
