i 24 Mind and Body 



function of consciousness in evolution. The fossils tell 

 nothing of any such factor as consciousness. Nor does 

 the embryo. So, as difficult as the ontogenetic question 

 is, it is one of the really hopeful fields on both sides. I 

 may be allowed, therefore, to give a brief summary of 

 certain results reached by the employment of this method ; 

 especially since it will set out more fully, even in its 

 defects and inadequacies, the general bearing of this 

 problem. 



That there is some general principle running through all 

 the conscious adaptations of movement which the indi- 

 vidual creature makes, is indicated by the very unity of the 

 organism itself. The principle of Habit must be recog- 

 nized in some general way which will allow the organism to 

 do new things without utterly undoing what it has already 

 acquired. This means that old habits must be substan- 

 tially preserved in tJie new functions ; that all new func- 

 tions must be reached by gradual modifications. And we 

 will all go further, I think, and say that the only way that 

 these modifications can be got at all is through some sort 

 of interaction of the organism with its environment. Now, 

 as soon as we ask how the stimulations of the environment 

 can produce new adaptive movements, we have the 

 answer of Spencer and Bain, an answer directly con- 

 firmed, I think, without question, by the study both of the 

 child and of the adult, by the selection of fit movements 

 from excessively produced movements, i.e., from move- 

 ment variations. So granting this, we now have the 

 further question : How do these movement variations come 

 to be produced when and where they are needed? 1 And 



1 This is just the question that Weismann seeks to answer (in respect to the 

 supply of morphological variations which the paleontologists require), with his 



