348 CARL VOEGTLIN 



interesting to note that different organs vary considerably in their vitamin 

 content. Thus Cooper(fc) (1913) has shown that the antineuritic vitamin 

 content is largest in ox liver, less in ox heart, and still less in ox brain and 

 skeletal muscle, the latter containing only relatively small amounts of this 

 substance (see also Osborne and Mendel (j) (fc), 1917, 1918). The pres- 

 ence of this vitamin was also demonstrated in the spinal cord (Voegtlin 

 and Towles, 1913), the pancreas (Eddy, 1916), the kidney (Osborne and 

 Mendel (;') (&), 1917, 1918), and testicle (Schaumanri, 1910) ; whereas it 

 seems to be absent from adipose tissue generally. These observations are 

 rather significant, as they suggest that the antineuritic vitamin is needed in 

 all tissues, more or less in proportion to the magnitude of their metabolism, 

 but not in tissues which function as a depot for reserve energy. This inter- 

 pretation is also supported by the fact that the yolk of eggs are rich in this 

 substance, whereas it seems to be absent in egg white. A similar deduction 

 may be drawn from the distribution of this substance in plant tissues, as it 

 was shown that it is concentrated within or in the immediate neighborhood 

 of the embryo or germ of the corn and wheat kernel and that it is absent in 

 the superficial layers and endosperm (Voegtlin and Myers (&), 1919). 

 More recent work has also shown that the green parts of plants contain 

 sonsiderable quantities of antineuritic vitamin, when due allowance is made 

 for the high water content of these foods (Osborne and Mendel (n), 1919). 



A somewhat different situation is met' with in the distribution in the 

 body of the fat-soluble vitamin, which is found not only in glandular 

 organs, but also in certain adipose tissue (beef fat). Strange to say, it is 

 absent from lard, and skeletal muscle appears to contain only traces. 

 Again, the liver is relatively rich in this substance, as shown by the 

 high activity of cod liver oil. 



Almost no data are available concerning the localization of the anti- 

 scorbutic vitamin in the various organs of the body, with exception of the 

 well established fact that fresh lean meat contains this factor. 



The numerous feeding experiments with deficient diets permit us to 

 conclude that the animal body, under normal conditions, contains a 

 considerable reserve of fat-soluble vitamin, but not of antineuritic and 

 antiscorbutic vitamin. Thus susceptible animals survive a much longer 

 period when supplied with a diet lacking in the former, than on a diet 

 deficient in the latter* two vitamins. 



As regards the role played by vitamins in metabolism, we are still 

 more or less limited to hypothetical considerations supported to some 

 extent by suggestive observations. One of the most perplexing questions 

 is the fact that different species of animals have different vitamin require- 

 ments. For instance, it is well proven that a diet complete in every respect 

 but completely lacking the antiscorbutic vitamin will support normal 

 metabolism, growth and maintenance of health in rats, mice, pigeons and 

 chickens for considerable periods, whereas this same diet will cause scurvy 



