338 THE VITAMINS 



till and Conklin, 1920) failures in reproduction in rats on diets con- 

 sisting chiefly of milk. In the second paper from this laboratory, Mattill 

 and Stone (1923) described degenerative changes in the reproductive 

 organs of male rats on diets in which all of the proteins and 

 A-itamins were furnished by milk. They noted also that the infertility 

 of female rats on these rations could not be explained by decline in 

 ovarian functions, since ox-ulation seemed to be taking place fre- 

 quently and the ovaries examined, though of small size, appeared to be 

 normal. 



Mattill and Carman (1923) reported that the sterility in male rats 

 on milk diets could not be prevented by the inclusion in the ration of 

 rich sources of vitamin B and concluded that "'the lack of some other 

 substance than vitamin B, and as yet tmrecognized, may be solely or 

 jointly concerned in the disappearance of the reproductive function." 

 Mattill, Carman, and Cla>-ton (1924) definitely accepted vitamin E, or 

 X as it was still designated at that time, as the missing factor in the 

 milk diets of their previous studies and reported success in the preven- 

 tion of this sterility by the various substances considered by Evans to 

 be rich in this vitamin. 



The statement by Sure (1926) that cottonseed oil contains vitamin 

 E and by Evans and Burr (1925a), confirmed by Kennedy and Palmer 

 (1926), that this is also true of hydrogenated cottonseed oil led Hogan 

 and Harshaw (1926a) to replace this component of their basal diet 

 with lard, following which change they were able to confirm Evans' 

 findings in every respect. The failure of Anderegg and Nelson to con- 

 firm the conclusions of Evans and of Sure was finally accounted for 

 by Nelson, Ohrbeck, Jones, and Taylor (1928) in the discovery that 

 the brand of cod-liver oil which they were using contained appreciable 

 amounts of vitamin E. In view of this accumulated evidence there 

 seems to be no longer any skepticism concerning the existence of vita- 

 min E. 



Determination of Vitamin E and Its Distribution in Food 

 Materials of Animal and Vegetable Origin 



The highly special technique required for ascertaining with cer- 

 tainty that the dietary sterility which is used as the criterion of vitamin 

 E deficiency is not due to other causes has served to retard such wide- 

 spread studies of the occurrence of this \-itamin as have been made of 

 the other vitamins. Moreover, too much reliance cannot be placed 

 upon the quantitative aspects of such studies as have been reported, 

 owing to the discovery noted elsewhere that vitamin E in any foodstuflF 



