94 THE BIOLOGY OF TWINS 



than between widely separated points; hence the 

 phenomenon of closer resemblance between pairs derived 

 from one-half of the egg. Evidently, too, as is brought 

 out better in another connection, certain symmetry 

 relations of the entire egg are established before the 

 formation of secondary growing points, and the residuum 

 of this early symmetric individuation is expressed 

 in mirror-image resemblances among the quadruplet 

 fetuses. 



