PLATE 4 



EXPLANATION OF FIGURES 



Hydractinia echinata 



30 and 31 Two drawings from the same nucleus, showing the reappearance 

 of the chromosomes in the form of crosses or parallel threads. X 1225. 



32 and 33 Two stages in the condensation of a cross-shaped chromosome. 

 X 1225. 



34 Various stages in the late condensation of the crosses and parallel threads 

 into tetrads, all found in the nucleus of figure 24. X 1818. 



35 Partially condensed tetrads arranged in an equatorial plate. X 1818. 



36 First polar spindle in the center of the nuclear area, showing astral radia- 

 tions which form a part of the heavy nuclear net caused by sublimate-acetic fix- 

 ation, X 600. 



242 



