342 Vitamines and Deficiency Diseases [June-September 



As a conclusion from these experiments we notice the complete 

 failure to demonstrate any special value of inorganic salts in the 

 process of growth; that even the addition of mixtures of salts to 

 artificial diets was unable to replace the important constituents of 

 natural diets. 



Value of lipoids and Phosphatids in growth. Iscovesco (107) 

 performed some experiments on growing animals with lipoid.iso- 

 lated by him from cod-liver oil or from the liver of codfish. This 

 lipoid could not be replaced in its action by any other lipoid. For 

 instance, for young rabbits he obtained the following figures for 

 increase in weight: Controls, 33 percent; cod-liver oil, 55 percent; 

 the same, without the lipoid, 37 percent; ohve oil, 33 percent; olive 

 oil, with the lipoid, 56 percent 



Desani (123) fed white mice with starch and casein that had 

 been extracted with alcohol and ether. This extraction was under- 

 taken in order to get a food free from cholesterol. The animals 

 died after 18-19 days with a loss of weight of 41 percent. 



McCollum and Davis (124) investigated the value of hpoids 

 from boiled eggs. The ether- and petroleum-extracts were effective 

 growth stimulants, the acetone extract only to a slight extent. 



Lander (125), who worked with a carefully purified diet, found 

 that rats live on such a diet about 14 days, the addition of choles- 

 terol, cholesterol esters and lecithin having no effect on growth. 



MacArthur and Luckett (126) proved that lecithin, cephalin, 

 cerebrosides and cholesterol are not vital dietary constituents for 

 mice; but they State that a fraction of egg-yolk insoluble in ether 

 and soluble in alcohol, probably vitamine (thermolabile), is neces- 

 sary to make a complete food. 



The above mentioned papers disprove the theory that lipoids are 

 necessary for the growth and maintenance of animals. 



Importance of pecuhar fats and oils for growth. A new 

 impulse in the study of the growth problem was given by the very 

 important discovery of McCollum and Davis (127) that butter-fat 

 or fat from egg-yolk is able to stimulate growth of rats which have 

 declined on artificial diets. This Observation was confirmed by 

 Osborne and Mendel (128) and extended by them (129). They 

 separated butter by centrifugation into three fractions, solid detritus, 



