Vi 



196 THEORETICAL BIOLOGY 



the wood, the plane that smooths it and the brush that var- 

 nishes it, is there any sort of chemical or mechanical connec- 

 tion enabling them to produce their effect in conformity 

 with plan ? In the external world is there anywhere, even 

 if it be in the brain of the several workmen, a chemical or 

 mechanical mosaic that would justify us in deducing by 

 analogy a similar mosaic in the germ of organisms ? Does 

 the manufacture of an implement take place according to a 

 materially existing pattern, or does it occur merely in accord- 

 ance with a plan following a given rule ? 



We can answer all these questions out of our own experi- 

 ence, because we ourselves are in a position to manufacture 

 implements. And we must acknowledge that the implements 

 we ourselves make are not mere creations of the mechanical 

 play of our muscles, but originate from actions, i.e. from the 

 mechanical performances of our limbs, guided by our impulse- 

 sequences, about which we ourselves know nothing. The 

 impulses, indeed, are factors about which we are quite 

 ignorant ; nevertheless, they are subject to definite rules. 



When we consider the actions of our fellow-men (even if 

 we leave out of account the whole question of conscious 

 sensations) we are obliged to assume certain conditioning 

 impulse-rules, if the plan expressed in these actions is to be 

 comprehensible. 



Let us now introduce into the germ of the nascent organism 

 the factors (which in the case of developing implements come 

 from outside), and let us recognise them as primary natural 

 factors ; the contradictions disappear which would other- 

 wise be inexplicable. The whole process of genesis then 

 resolves itself into a series of independent actions held together 

 in equipoise by impulse-rules. 



The theory of factors requires no invisible, hidden frame- 

 work to make plausible the plan underlying the genesis of 

 the nascent organism. The theory of factors takes this plan 



