I9I5-] THE HEREDITARY MATERIAL. 153 



To say that the germinal material that makes a white eye is dif- 

 ferent from the germinal material that makes a red eye is a plati- 

 tude. But to be able to locate a particular material in the one case 

 in relation to other materials is a very different matter, because by 

 means of this information we are able to explain the results on a 

 mechanistic basis, and are able to predict the results of untried 

 combinations. Without this information the prediction would be 

 impossible. 



We are led then to a third conception of predetermination. It is 

 this ! That while the hereditary material is made up of different 

 discrete and separable particles (chemical substances) that have a 

 definite position in the chromosomes, the effects of each of these 

 particles must be supposed to be produced in combination with 

 many, or even with all other parts of the cells in which they are 

 contained. 



Columbia University, 

 New York. 



PROC. AMER. PHIL. SOC, LIV. 217 K, PRINTED JULY 7, I9I5. 



