THE LIVING ORGANISM 233 



been named hormones, or excitants, by Bayliss 

 and Starling. In certain cases the chemists 

 have been able to isolate these hormones, 

 and in one case the chemical constitution is 

 known and the substance has been manu- 

 factured artificially in the laboratory. In 

 other cases, and these the majority, they 

 are as yet only known by their definite 

 stimulating action. Quite recently it has 

 been shown that bodies similar in nature 

 to the hormones must be present in our daily 

 diet, or certain typical nutritional diseases 

 are produced. These hormones are not foods 

 in the sense of being necessary to provide 

 energy by their combustion ; they are only 

 required in minute amounts as excitants, and 

 in their absence certain very specific effects 

 giving the clinical symptoms of well-known 

 diseases appear. In a liberal and mixed diet 

 all the necessary hormones required from 

 outside are contained. But, when the diet 

 is very restricted, such as the rice diet, 

 used by the Indian coolie, unless the thin 

 brownish layer surrounding the inner white 

 part of the rice be eaten in the daily diet, 

 a disease with marked nervous lesions appears, 

 called beri-beri. This disease long puzzled 

 medical scientists, but it is now clearly shown 

 to be caused by the absence from the diet 



