126 THE VITAMINES 



other was given a complete diet. Both mice were kept alive, showing 

 that the one animal received with blood, not only the usual dietary 

 constituents, but also the vitamines. 



Of the important investigations on mice, we shall first mention 

 those of Stepp, upon whose work of 1909-1911 we have already 

 touched lightly. He extracted the whole diet, thereby partly remov- 

 ing and partly destroying the vitamines. In this way, he obtained 

 mixed avitaminoses that could be attributed to the lack of at least 

 two vitamines. He proved (348) that lecithin, cholesterol, kephalin 

 cerebron and phytin could not replace the substances extracted by 

 alcohol-ether mixture. He found also that while the important sub- 

 stances could not be removed by means of the ether extraction alone ; 

 they could be removed with alcohol alone. When egg-yolk is 

 extracted with alcohol, these substances go into solution, but not 

 when acetone is used. Following this, Rohl (349) found that ordinary 

 commercial lecithin contained these substances, while pure lecithin 

 did not. In a publication appearing in 1914, Stepp (350) drew close 

 to the prevailing view of the importance of two vitamines in the life 

 of mice although he still thought of the fat vitamine as a lipoid. 

 In 1916, Stepp (351) advanced a step further in that he used two 

 different extracts, one of egg-yolk and the other of rice polishings 

 (orypan). However, the experiments in this case were not very 

 clear, since at first Stepp worked with a vitamine mixture (egg-yolk), 

 believing he had to deal with a lipoid. Furthermore, he showed (352) 

 that a mixture of lecithin, kephalin, cerebron, cholesterol and orypan, 

 added to dog biscuit which had been extracted with alcohol, could 

 at least maintain mice at a certain level. It is, however, not impos- 

 sible that this was due to a cumulative action of vitamine A con- 

 tamination. Dezani (353) conducted experiments for the purpose 

 of determining the source of cholesterol. He fed mice on flour and 

 casein, extracted with alcohol and ether. The animals died after 

 18 to 19 days, showing a 41 per cent loss in weight. Cholesterol 

 was found in the feces, and Dezani (354) was of the opinion that mice 

 could be kept alive on a lipoid-free diet. We may mention here one 

 of the typical experiments of Rohmann (355), in which mice were 

 raised on a diet of casein, chicken protein, nucleoprotein from liver, 

 potato starch, margarine and a salt mixture. This food proved to 

 be inadequate and the animals grew less than on milk and rolls. The 

 substitution of vitellin for nucleoprotein did not yield any better 



