THE FACTORIAL HYPOTHESIS 265 



In the following sections, several of the more im- 

 portant misconceptions arising from the confusion 

 between factors and characters will be considered 

 in turn: 



1. There is a curious objection to the factorial 

 hypothesis that is sometimes brought forward. It 

 originated apparently as an objection to Weismann's 

 idea that a single determinant stands for a single 

 character. Weismann's idea of a sorting out of 

 determinants undoubtedly implies something of this 

 kind. The objection states that the organism is a 

 whole — that the whole determines the nature of the 

 parts. Such a statement, in so far as it has any 

 meaning at all, rests on a confusion of ideas. That 

 the different regions of the developing embryo do 

 sometimes have an immediate influence on each other 

 has been abundantly demonstrated, as well as the 

 fact that in other cases parts have little or no in- 

 fluence on each other. That substances are pro- 

 duced in one place whose principal effects are seen 

 in other places is not likely to be denied. It has 

 even been insisted in the preceding pages that the 

 evidence from heredity indicates with great proba- 

 bility that there are many factors whose combined 

 effect is necessary for the production of each separate 

 character, as in the production of eye color, for 

 example. There is no reason why this interaction 

 should always take place within the separate cells; 

 in other words, why the products of factor A in one 

 cell should not sometimes affect the products of 

 factor B in another cell. The factorial hypothesis 



