PLATE 5 



EXPLANATION OF FIGURES 



Hydractinia echinata 



37 The first polar spindle (having no asters) in the center of the homogeneous 

 nuclear area, which is characteristic after Meves' fixation. X 600. 



38 The first polar spindle, showing the tetrads becoming arranged at the 

 equator. X 2625 



39 and 40 Two equatorial plates of the first polar spindle, showing 15 and 14 

 chromosomes respectively. X 2625 



41 Section to show the arrangement of cell-elements before fertilization. 

 X 2625 



42 Section to show rearrangement of mitochondria and fertilization membrane 

 after entrance of the sperm. X 2625. 



43 to 45 Three stages in the formation of the first polar body, the spindle 

 having moved out of the nuclear area which remains as two homogeneous areas in 

 the protoplasm. X 2625 



46 The formation of the second polar body. The first polar body shows 14 

 chromosomes. X 2625 



244 



