FOODS AND DIETETICS. 89 



Saccharose, or cane-sugar . . . Sugar-cane. 



Dextrose, or glucose , _ . 



V Fruits. 



Levulose, or fruit-sugar . . . . j 



Lactose, or milk-sugar .... Milk. 



Maltose Malt, malt foods. 



Starch Cereals, tuberous roots, and legu- 

 minous plants. 

 Glycogen Liver, muscles. 



4. Inorganic Group. Water ; sodium and potassium chlorids ; sodium 

 calcium, magnesium, and potassium phosphates ; calcium carbonate ; 

 and iron. 



5. Vegetable Acid Group. Malic, citric, tartaric, and other acids, 

 found principally in fruits. 



6. Accessory Foods. Tea, coffee, alcohol, cocoa, etc. 



The proteid principles of the food, after undergoing digestion and 

 conversion into peptones, are absorbed and transformed into the 

 form of proteids characteristic of the blood plasma and the lymph. 

 Of the proteids thus brought into relation with the living protoplasm, 

 a small percentage only is utilized in the repair of its substance. 

 This is known as tissue proteid. A large percentage circulating 

 among and permeating the tissues is acted upon by them directly, 

 and reduced to simpler compounds without ever becoming a part 

 of the tissue itself. This is known as circulating proteid. In the 

 process of tissue metabolism all the proteids suffer disintegration, 

 and give rise to the production of some carbon-holding compound, 

 probably fat, and some nitrogen-holding compounds which eventually 

 produce urea. The intermediate stages are possibly represented by 

 glycin, creatin, uric acid, etc. An excess of proteids in the food 

 is followed by their decomposition, by the pancreatic juice, into 

 leucin and tyrosin, which, by the agency of the liver, are converted 

 into urea. The disintegration of the proteids is attended by the dis- 

 engagement of heat : they thus contribute to the energy of the body. 



The oleaginous principles, after digestion, are absorbed into the 

 blood, from which they rapidly disappear. It is probable that a por- 

 tion of the fat enters directly into the composition of living proto- 

 plasm, out of which it again emerges at some subsequent stage in the 

 form of small drops which make their appearance in the protoplasmic 

 cells of the connective areolar tissue, thus giving rise to the adipose 

 tissue. Another portion probably undergoes direct oxidation. 



