CHAPTER XII 



OUTLINES OF THE CHEMISTRY OF ALBUMINS 

 OR PROTEINS 



ALL living organisms contain as an essential constituent a 

 highly complex nitrogen-containing substance known gene- 

 rally as protoplasm. The simplest of all organisms, e.g., the 

 amoeba, is virtually a simple mass of protoplasm ; it has the 

 property when alive of dividing into smaller living portions, 

 and of building itself up from elements absorbed from its 

 external surroundings. 



The most highly developed animal, chemically considered, 

 is a vast aggregation of cells of different structure and function, 

 but all of them containing protoplasm in some form or other. 

 Protoplasm is in no sense a chemical entity with a definite 

 composition such as may be ascribed to even highly com- 

 plicated organic substances ; it possesses structure visible 

 under the microscope, and must be looked upon when alive 

 as a constantly changing complex, wherein loose combina- 

 tions are constantly being formed and decompositions taking 

 place. Protoplasm may indeed be regarded as a factory where 

 raw material of various kinds is taken in, where finished 

 products are delivered, and where a certain amount of waste 

 material is produced. 



It would obviously be of little help to the understanding 

 of the operations of such a factory simply to know the materials 

 of which it is composed, or even the bare enumeration of its 

 contents in terms of iron and steel and bricks and mortar or 



