494 THE EVOLUTION OF LIFE. 



that of Dr. Darwin; and along with the truth it contains, 

 contains also the same error more distinctly pronounced. 

 Merely noting that desires or wants, acting directly only 

 on the nervo-muscular system, can have no immediate in- 

 fluence on very many organs, as the viscera, or such external 

 appendages as hair and feathers; and observing, further, 

 that even some parts which belong to the apparatus of ex- 

 ternal action, such as the bones of the skull, cannot be made 

 to grow by increase of function called forth by desire; it 

 will suffice to point out that the difficulty is not solved, but 

 simply slurred over, when needs or wants are introduced as 

 independent causes of evolution. True though it is, as Dr. 

 Darwin and Lamarck contend, that desires, by leading to 

 increased actions of motor organs, may induce further de- 

 velopments of such organs; and true, as it probably is, that 

 the modifications hence arising are transmissible to offspring ; 

 yet there remains the unanswered question — Whence do these 

 desires originate? The transference of the exciting power 

 from the exterior to the interior, as described by Lamarck, 

 begs the question. How comes there a wish to perform an 

 action not before performed? Until some beneficial result 

 has been felt from going through certain movements, what 

 can suggest the execution of such movements? Every desire 

 consists primarily of a mental representation of that which 

 is desired, and secondarily excites a mental representation of 

 the actions by which it is attained; and any such mental 

 representations of the end and the means, imply antecedent 

 experience of the end and antecedent use of the means. To 

 assume that in the course of evolution there from time to 

 time arise new kinds of actions dictated by new desires, is 

 simply to remove the difficulty a step back. 



§ 146. Changes of external conditions are named, by Dr. 

 Darwin, as causes of modifications in organisms. Assigning 

 as evidence of original kinship, that marked similarity of 

 type which exists among animals, he regards their devia- 



