6o THE PH YSICAL BASIS OF INHERITANCE 



the important parts, and it is the ovum which furnishes the 

 cytoplasmic basis of further operations. The very gist of 

 fertihsation, so jar as we can see it, is the intimate and orderly 

 combination of the paternal and maternal chromosomes to 

 form one nucleus — the segmentation-nucleus. Moreover, the 

 maternal and paternal contributions are, as we have noted, 

 distributed with scrupulous equality, certainly to the first two 

 cells of the embryo, and probably to all later-formed cells. 



" The latter conclusion, which long remained a mere surmise, 

 has been rendered nearly a certainty by the remarkable ob- 

 servations of Riickert, Zoja, and Haecker. We must, therefore, 

 accept the high probability of the conclusion that the specific 

 character of the cell is in the last analysis determined by that 

 of the nucleus — that is, by the chromatin ; and that in the 



