VlTAMINE A. 



243 



elusive diet of dry whole milk. Of the two limiting factors which 

 she indicated, protein and inorganic salts, the latter appears to 

 be the more important; but on a dried milk ration supplying both 

 of these factors in added amounts the rearing of young has not 

 been generally successful. On a food consisting of dried whole 

 milk 93 per cent., salt mixture 2 per cent, and yeast 5 per cent., 

 we have now obtained a fourth generation. Animals on this food 

 without yeast (98 per cent, milk powder, and 2 per cent, salt 

 mixture, with an additional 0.2 per cent. Fe citrate) become preg- 

 nant and young are born, but they are small and scrawny in ap- 

 pearance and usually die within 3 or 4 days. Sometimes no trace 

 is found of these litters, the only evidence being the drop in 

 weight of the female. What constituent of yeast is responsible 

 for the successful reproduction secured by its addition remains 

 to be determined by the work at present under way. 



122 (1704) 



The presence of vitamine A in the peel of common citrous fruits 



By ETHEL COOPER (by invitation). 



[From the Hull Physiological Laboratory, The University of Chicago.] 



About a year ago, preparations of orange peel were added to a 

 diet otherwise free from the fat soluble vitamine. The possi- 

 bility that such preparations might contain fat soluble A was 

 based on the hypothesis of Steenbock 1 that the fat soluble vitamine 

 is a yellow vegetable pigment or a closely related chemical com- 

 pound. 



The peels used for a determination of their fat soluble vitamine 

 content were faultless and of the deepest yellow color. The outer 

 surface of the dried peels was grated enough to break the tiny 

 pockets which contain the yellow oil. Peels and gratings were 

 then extracted on the water bath with ether and alcohol. These 

 extracts were evaporated down to dryness. The gummy mass 

 thus obtained was stirred thoroughly into a diet otherwise free 

 from fat soluble vitamine and then fed to a number of white rats. 

 The results yielded indubitable evidence that the waxes and oil 



1 Steenbock, Science, 1919, i, 352. 



