METABOLISM 197 



of the animal the nitrogen excretion rises sharply. This is known 

 as the pre-mortal rise. It appears as if the organism gives up 

 the struggle to protect its tissues from destruction and that the 

 overtaxed organism begins to give way. After a prolonged fast, 

 the total nitrogen excretion in man falls to the neighborhood of 

 about 2 grams per day. This appears to be the minimum, and 

 has been taken by some to represent the actual necessary wear 

 and tear of the protein tissues of the body. Possibly, however, it 

 is necessary for the body to break down the protein which this 

 represents in order to obtain some particular amino acid or 

 acids needed in the synthesis of some absolutely essential prod- 

 uct of internal secretion. 



Several cases are on record, and the author himself has known 

 individuals who have derived great benefit from an occasional 

 wisely timed fast. The digestive and excretory organs are given 

 a rest, the tissues are cleared of all unnecessary stored up ma- 

 terial, and the body undergoes a thorough housecleaning. 



Unknown Food Constituents. Vitamines. Until recently it 

 was believed that if an individual were supplied with enough 

 protein, the necessary salts, and amounts of carbohydrates and 

 fats sufficient to make up the total of energy required, that his 

 diet was adequately regulated. Recent developments have 

 shown that this list is incomplete, and that certain substances 

 hitherto undreamed of, are absolutely essential to the health and 

 even the life of the individual. The chemical nature of these 

 substances is still unknown, but it appears that there are at 

 least two and possibly more of them. 



The discovery of the existence of these substances was inti- 

 mately connected with a disease known as beri-beri prevalent in 

 oriental countries where the natives live on a diet consisting 

 mainly of polished rice. On such a diet, extensive disturbances 

 of the nervous system develop, resulting in weakness, paralysis 

 and ultimate death. Feeding the outside layer of rice, ordi- 

 narily removed in polishing, causes immediate relief and speedy 

 recovery. A substance evidently is present in the outer layer 

 of rice, without which an animal on a polished rice diet devel- 



