270 THE VITAMINS 



per gram, which if confirmed would be significantly different from nuts 

 as a whole. 



Drummond and Coward (1920a) indicated that "no hard and fast 

 line can be drawn between animal and vegetable oils and fats when 

 their value as a source of vitamin A is being considered" but that 

 "taken as a class the animal fats possess a growth-promoting power 

 superior to that of the vegetable oils." Later, concerning seed oils 

 (which constitute the majority of oils from plant sources), Drummond 

 and Zilva (1922) state that "the majority of the vitamin in the seed 

 passes into the oils, producing oils of very low potency as compared 

 with the chief animal oils and fats." As has been indicated, reports of 

 a trace or failure to detect measurable quantities may be due to faulty 

 methods of testing. Therefore plant oils which have been found to 

 contain none or only a trace may be classed in one group. This includes 

 the oil of almonds, arachis, castor beans, coconuts, cottonseed, djave, 

 grapefruit peel, hempseed, linseed, mafurreira, mustard seed, olives, 

 peanuts, rapeseed, sesame seed, Siak Illipe nuts, soy beans, and sun- 

 flower seeds. 



The vitamin A content of animal products is now known to be 

 ultimately dependent upon the diet of the animal but influenced by 

 the reserve store in the body. 



The distribution of the vitamin among the various tissues of the 

 body has been studied quantitatively (Sherman and Boynton, 1925). 

 "If adipose tissue and skin be ignored, about nine-tenths of the total 

 vitamin A in the body of a well nourished rat was found in the liver 

 and the remaining tenth about equally divided between the muscles as 

 a whole, the blood, the kidneys, and the lungs. Weight for weight, 

 kidney was about 40 times, lung more than 40 times, and liver between 

 200 and 400 times as rich in this vitamin as is muscle. Moderate differ- 

 ences in the vitamin A content of the food, such as are well within the 

 range of variation likely to be encountered in human experience, re- 

 sulted in large differences in concentration of this vitamin in the liver, 

 and distinct differences in the amount of it found in lung tissue." 



Therefore among the animal products which are used as food, the 

 muscle tissues are poor in vitamin A while glandular organs, animal 

 fats and oils, eggs, milk and milk products are usually much richer 

 sources. Indications in reported studies on the muscle of beef, codfish, 

 haddock, lamb, pig, poultry, rat, salmon and veal, are that they contain 

 from traces to 0.5 unit of vitamin A per gram. On the other hand, 

 glandular organs which have been investigated have always contained 

 markedly more unless taken from animals whose food had been de- 



