APPETITE OF SWINE 
383 
ether extract of the ripe testicle of the cod fish”, — negative find- 
ings being evident with commercial lard, olive oil, cottonseed oil, 
and tallow. Osborne and Mendel found cod-liver oil and the 
lighter oils of beef fat to have the special effective virtues, but 
not so almond oil. 
Recently McCollum and Davis^^ have demonstrated that the 
favorable substance — or rather similar effects as produced from 
the effective fat feeding — is noted in the feeding of corn grain 
(fed in toto). Seemingly, the other grains such as wheat, rye, 
and oats are not nearly so effective although the separated wheat 
embryos, give quite marked results. 
To make this ‘‘Fat” matter a bit more elucidative a represen- 
tative concrete example may be in order : Certain rats are fed on 
a definite mixture of food constituents of which lard comprises 
a portion of the ration, it being the lone source of fat. For a 
few months, these rats appear to prosper, but lot and behold! 
after these preliminary days of apparent success they cease to 
gain in weight, — in truth shortly begin to decline — the ultimate 
disaster being death if the lard or a portion of it is not replaced 
with an effective fat or oil. Substitute the lard with olive, or 
cottonseed oil and the results are absolutely negative, but use 
butter-fat or cod-liver oil, and the rats take on new life, cease 
traveling the “downward road that leads to earthly oblivion” 
and begin to mend, their weight increases, and sooner or later, 
if the decline is not carried to the point of bodily collapse, grow 
again into good, healthy, active, nimble, sleek-looking rats. 
Stepp^^ has likewise pioneered in these fat investigations and 
his studies are interesting in that tripalmitin, tristearin, and 
triolein were not effective in bringing his “experimentally de- 
clined” mice back to health. Stepp affirms that the particular 
effective substances, soluble in alcohol-ether are not fats. 
Cooper^^ has recently shown that this decline is not due to the 
absence of lipoids from Stepp’s alcohol-ether extractions, as he 
(Stepp) suggested, but to the transfer of the vitamines of the 
2iMcCollum, E. V., and Davis, Marguerite : The Influence of Certain 
Vegetable Fats on Growth, Jour. Biol. Chem., 1915, XXI, 179. 
2^Stepp, W. : Versuche iiber Fiitterung mit lipoidfreier Nahrung, Biochem. 
Ztschr., 1909, XXII, 452 ; Fiitterungsversuche mit lipoidfreier Nahrung, Ver- 
handl. d. Kong. f. inn. Med., 1911, XXVIII, 324 ; Experimentelle Untersuch- 
ungen iiber die Bedeutung der Lipoide Fiir die Ernahrung, Ztschr. f. Biol., 
1911, LVII, 135; Experiment iiber die Einwirkung langdauernden Kochens 
auf lebenswichtige Nahrungslipoide, Verhandl. d. Kong. f. inn. Med., 1912, 
XXIX, 607 ; Weitere Untersuchungen iiber die Unentbehrlichkeit der Lipoide 
fiir das Leben, Ueber die Hitzezerstorbarkeit lebenswichtiger Lipoide der 
Nahrung, Ztschr. f. Biol., 1912, LIX, 366 : See Mendel, Lafayette B. : Note 
15, also. 
2=^Cooper. Evelyn A. : The Relations of Vitamines to Lipoids, Biochem. Jour. 
1914, VIII, 347. 
