THE CONCEPT OF EVOLUTION 371 



tial nature (due, probably, to causes of a higher order than 

 those of the material universe) took place at the several 

 stages of progress which I have indicated ; a change which 

 may be none the less real because absolutely imperceptible 

 at its point of origin, as is the change that takes place in 

 the curve in which a body is moving when the application 

 of some new force causes the curve to be slightly altered ' 

 (Darwinism, 1889, p. 476). 



Without confining ourselves to Wallace's position, let us 

 inquire into the theories of spiritual influx. () In some 

 forms they amount to a premature abandonment of the sci- 

 entific mode of attacking the problem. For scientific formu- 

 lation proposes to work with verifiable factors, and that can- 

 not be said of spiritual influxes operating in organic evo- 

 lution. We see reason for attaching much importance to 

 the influence of mind in evolution, a capacity for be- 

 haviour of which we cannot give a protoplasmic account, 

 but this is amenable to experimentation and to verification 

 by competent observers. (&) A spiritual influx theory is 

 apt to be associated with a fanciful dualism, implying two 

 worlds, one of which only occasionally intrudes effectively 

 into the other. This means an abandonment of the idea of 

 continuity of process. There are some who regard the 

 biologist's conviction of a process without gaps as an illu- 

 sion, who frankly avow their belief in extrinsic factors of 

 another order than those admitting of scientific study, which 

 now and again move organisms like puppets in a show; and 

 Wallace spoke of " a change in essential nature (due, prob- 

 ably, to causes of a higher order than those of the material 

 universe) ". This view may seem to us to break the law 

 of parsimony, but it would be difficult to prove it false. 

 What we cannot accept, however, is Wallace's assurance 



