WHAT IS LIFE 



organisms many of its cells die and are replaced by 

 other cells, the process of regeneration in some of the 

 simpler organisms even extending to the replacing 

 of lost parts. As Hans Driesch insists, it is "the whole 

 that uses the cells." Therefore, to describe the in- 

 dividual cells of the higher life-forms does not de- 

 fine the organism. 



Cells are extremely complex both in chemical con- 

 stitution and in structure, and of great variety, as 

 shown by the vast body of facts of cytology. ^ The 

 absolute specificity of the constitution and functions 

 of the cell is shown in heredity, in which a host of 

 specific traits as well as the general characteristics of 

 the parent form are reproduced — and this in hundreds 

 of thousands of different life-forms. 



Obviously, the mere fact of the specificity of the 

 germ-cell throws no light whatever on what is the 

 essential nature of the process that determines the 

 successive generations of organisms by means of 

 the germ-cell. 



The problem of life in its simplest form is the prob- 

 lem of protoplasm. But in the nature of things 

 protoplasm cannot be analyzed. As Woodruff states: 

 "From one point of view it is impossible to analyze 

 protoplasm because the least disturbance of its fun- 

 damental organization results in a cessation of those 



^ See Edmund B. Wilson, The Cell in Development and Heredity. 



