CHAPTER VII 

 VITAMIN E 



Evans and Bishop (1922, 1923a) found that rats kept for rela- 

 tively long periods of time upon mixtures of purified foodstuffs and 

 with ample provision for all previously known vitamin requirements 

 finally showed evidence of needing, for successful reproduction, an 

 hitherto unknown fat-soluble substance which they tentatively called 

 "X," but which later, in accordance with the chronological alphabetical 

 sequence first suggested by McCoUum, became known as vitamin E. 

 Descriptively, this vitamin is often referred to as the "antisterility" 

 vitamin or the "vitamin of reproduction." These terms are unfortunate, 

 for while vitamin E is undoubtedly essential to reproduction, it is cer- 

 tainly no more so than vitamin A. A diet devoid of vitamin A stops 

 reproduction quite as certainly and may stop it quite as quickly as one 

 devoid of vitamin E. Vitamin E, therefore, is no more directly or 

 essentially concerned with reproduction than is vitamin A, and because 

 of its more widespread occurrence is probably of less practical impor- 

 tance than vitamin A. The greater emphasis upon the sterility-prevent- 

 ing properties of vitamin E than of vitamin A is probably due to the 

 fact that this is its chief function, while vitamin A, as has been shown 

 in Chapter V, has many other important functions in addition to its 

 essential part in the nutritional processes of reproduction. 



Lack of vitamin A causes failure of reproduction through inter- 

 fermg with ovulation, whereas lack of vitamin E interferes with 

 placental function. These two disturbances of the reproductive process 

 are clearly distinguished by the histological technique developed and 

 used by Evans and his collaborators who feel that if this technique is 

 followed carefully there is no danger of shortage of either one of these 

 vitamins being mistaken for a shortage of the other. In their opinion 

 the steriHty caused by lack of vitamin E can be recognized in the living 

 animal only by following each step in the reproductive process. Evans 

 and Burr (1927d) have emphasized in their memoir on vitamin E that 

 in all studies of reproduction "almost no knowledge is gained by merely 

 placing animals of the opposite sex together and ascertaining that in- 

 fertility results." 



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