THE CONQUEST OF DISEASE 



in hungry animals. Subsequent studies showed 

 them to be minute lymphatic channels through 

 which the hydro-carbon foods were absorbed 

 and conducted into the blood through the 

 thoracic duct. Our best formulated knowledge 

 of the relations of foods to nutrition has been 

 secured through feeding experiments upon 

 animals. The determination of nutritive 

 values, the discovery of the role of sodium 

 chlorid and other salts, and the actual nutritive 

 requirements of the infant have been found 

 by such means. 



Now the physiologist takes an animal or a 

 man; he measures accurately each food that 

 he takes; knows the weight of the body; ex- 

 amines every excretion as to its chemical com- 

 position, even to the exhalations from the 

 lungs ; and is able to know the transmutations 

 through which the nourishment passes ; and by 

 making measured tests of the strength of the 

 muscles, including the heart, he can learn the 

 value of foods. The relation of food to health 

 and energy is now the subject of careful animal 

 experimentation, and the day is near when we 

 shall eat more wisely as a result of it. 



This whole subject of internal secretions of 

 glandular structures is being worked out 



