GENERAL METHODS — HISTORY OF PROTEIN FOOD. 



905 



simply, by using the juice of lemons or oranges. This experience 

 has been confirmed by the results of feeding experiments upon 

 animals and men. Scurvy is now recognized as a deficiency dis- 

 ease due to the absence of the antiscorbutic vitamin in the diet. 

 This vitamin occurs chiefly in the fruits, particularly in oranges, 

 lemons, and tomatoes, and in the leafy parts of vegetables. It is 

 the least resistant of the thi-ee vitamins. Heating, drying, and 

 other methods of food preservation usually destroy it, with the 

 exception that in the case of fruits and tomatoes the process of 

 canning leaves it effective, in part at least, owing to the protective 

 action of the acids. It is stated, however, by Delf* that this 

 vitamin withstands heating above 100° C. if the heating is con- 

 ducted in the absence of air. Orange juice is especially resistant, 

 so that the antiscorbutic factor in this case may be obtained in a 

 concentrated and stable form by drying. 



The distribution of these three vitamins among our commoner 

 foods is indicated in the accompanying table, f the plus, double 

 plus, and triple plus signs indicating increasing amounts of the 

 vitamin : 



TABLE SHOWING THE DISTRIBUTION OF THE VITAMINS IN 

 SOME OF THE COMMONER FOODS 



Butter 



Cod-liver oil 



Mutton fat 



Beef fat 



Fish oil 



Lard 



Olive oil 



Lean meat 



Liver 



Milk 



Eggs 



Cabbage (fresh) 



Lettuce . 



Lemon and orange juice . . . 



Tomatoes 



Yeast (dried) 



Wheat flour, cornmeal, rice 

 Meat extracts 



Water- 

 soluble C. 



+ 

 + 

 + 



+ + + 



+ + + 

 + + 





 



As stated above, the role that the vitamins play in the met- 

 abohsm of the body is entirely unknown. It has been suggested 



* Delf, "BiochemicalJournal," 14, 211, 1920. 



t Taken from the larger table in the general report of the Medical Ke- 

 search Committee, Special Report Series, No. 38, 1919, London. 



