DIETETICS 159 



tions (a) the bioplasm ; (b) the food-proteins in contact with 

 it. It is inferred that gelatin, although it cannot be built up 

 into bioplasm, may take the place of proteins present in the 

 cell-juice. It appears to be impossible to starve the cell 

 until it consists of a bioplasm framework bathed in nitrogen- 

 free cell- juice. As the non-living proteins of cell- juice are 

 removed, they are, if no nitrogenous food be given, renewed 

 by the breaking down of bioplasm. When gelatin is absorbed, 

 it takes its place in the cell- juice, and the breaking down of 

 bioplasm is no longer necessary. When digestion is impaired, 

 or vitality lowered, decoctions of meat which contain extrac- 

 tives of low calorific value, useless, without synthesis (cf. 

 p. 144), for the purposes of tissue-repair, may to a certain 

 extent save tissue-waste. In the same way, gelatin, which is 

 very rapidly digested in the stomach, may cover the consump- 

 tion of proteins, although it cannot take their place. 



To sum up : The requisite daily income of energy must 

 come from both nitrogenous and non-nitrogenous food. It 

 is impossible to reduce the nitrogenous factor below a certain 

 minimum. From this minimum upwards, until a certain level 

 is reached, every additional unit of nitrogenous food enables 

 the system to dispense with more than its equivalent of non- 

 nitrogenous food. When the proper balance of foods is 

 attained, there is no waste either of labour involved in 

 digestion, or of labour involved in metabolism and excretion. 



The Liver. The liver weighs from 3 to 3J pounds. It lies 

 beneath the diaphragm, more on the right side than on the left. 

 Its posterior border, which rests against the last three ribs 

 (separated from them by the diaphragm), is about 3 inches 

 thick. Its anterior border is thin, and keeps close along the 

 line of the ribs. If the organ is neither unduly enlarged nor 

 squeezed out of its place owing to the use of a tight corset, 

 it does not project below the ribs, save where it crosses the 

 space between the rib-cartilages below the end of the breast- 

 bone. 



The liver is supplied with blood by the hepatic artery. 

 This vessel is small for so large an organ. Although 

 responsible for the nutrition of the liver, it does not bring it 

 the materials which are stored in its cells. A much larger 

 supply of blood is derived from the portal vein, which breaks 



