THE REACTION TO FOOD 333 



economical choice of food, and that the farmer could readily 

 calculate the most economical combinations of feeding 

 stuffs which would supply the necessary protein and energy 

 for animal production, milk and egg production, etc. 

 Soon after 1900 it became possible to begin the appHcatlon 

 of this Hne of reasoning in the feeding of farm animals, and 

 the fact came to light that two diets might have the same 

 chemical composition so far as analysis can show, yet one 

 might be highly satisfactory and the other a complete failure 

 from the physiological standpoint. It became evident, there- 

 fore, that the chemical procedure in analyzing foods has 

 distinct hmltatlons and that there are qualities in foods which 

 even the most searching analysis cannot reveal. 



As early as 1843 Pereira in a book, "A Treatise on Food 

 and Diet, "called attention to the fact that there must 

 be other principles than aqueous, saccharine, albuminous, 

 and oleaginous principles in lemon juice, which was known 

 to be a valuable food in the treatment of scurvy, for he 

 pointed out that it did not owe this property to any of the 

 principles recognized by chemists. 



As early as 1881 Lunin in Germany had attempted to 

 feed laboratory animals on mixtures containing exactly 

 those principles which the chemist determines in his analysis, 

 proteins, carbohydrates, fats, and a mixture of those min- 

 eral salts known to be normal constituents of the animal 

 body. He made the interesting and unexpected discovery 

 that such diets were inadequate, although from a standpoint 

 of chemical analysis they appeared to be complete. It was 

 many years before this subject was again studied in an 

 effective way. Wide publicity was given to Lunin's results 

 In a much used textbook by Bunge, and these doubtless 

 led to many speculations by physiologists. 



In 1905 Pekelharing in Holland published experiments 

 comparable to those of Lunin. He fed white mice on a bread 

 of casein, albumin, rice flour, lard and a mixture of all the 

 salts which ought to be found in their food, and gave them 

 water to drink. He observed that they all starved to death, 

 even though they ate greedily of the food In the beginning. 

 He further showed that if instead of water they were given 

 milk to drink they continued to thrive. He established the 



