THE LAMARCKIAN THEORY 



543 



which seem in many instances to be set apart from the body cells 

 at an early period and to be relatively uninfluenced by them. If 

 the Lamarckian scheme holds, one must suppose that a change in a 

 given part of an animal is transferred to the germ cells in such a 

 way as to affect whatever it is in the germinal material that causes 

 the development of this part. A blacksmith's son inherits his 

 arms not from his father's arms but through his father's germ cells, 



Fig. 299. — Cypress trees in the Dismal Swamp, Va. 



The "knoes" or pointed growths from the roots that project upward and are supposed 

 to aid in aeration are not produced when the same species of tree grows on dry land. They 

 are evidently a modification due to environment and not inherited. (After Russell, U. S. 

 Geol. Survey, reprinted by permission from Pirsson and Schuchert, " Textbook of Geology," 

 John Wiley & Sons, copyright, 1924.) 



and so the germ cells of the father must have been changed if any 

 modification has been inherited. The facts of animal structure 

 and function make it difficult to understand how such influences 

 can be transferred, but it is not necessary to picture such a process 

 so long as there is no satisfactory evidence of its occurrence. This 

 theoretical objection merely confirms the conclusions drawn from 

 the failure of experimental evidence, although it would not be 



