PLATE I 



EXPLANATION OF FIGURES 



1 Nucleus in growth period. 



2 to 11 Stages in the opening up of a longitudinally split thread to form a ring. 

 12 to 17 Shows twisting and bending in opening to form a ring. 



18 to 24 Different stages of ring formation in the same chromosome by bending 

 and the condensation of this ring into a bivalent chromosome. 

 25 to 30 Ring formation by bending in another chromosome. 



582 



