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 
