PLATE m. 



Fig. 41. 



Fig. 42- 



Fig. 43- 



Fig. 44. 

 Fig. 45. 



Fig. 46. 



Beroë ovafa. xGO (with the exception of Fig. 44 xl02). 



Egg cut horizontally below the " head." The enucleated cytoplasm cut off 

 did not show any division activity. 



Egg cut below the " head " liorizontally nearly two third of its diameter. 

 10.15 AM. 



The same. 10.38 AM. 



Egg cut in two horizontally at the stage when the " head " liadcome down 

 nearly two-tbirds of its course, 10.10 AM. 



Enucleated fragment of the same showing ectoplasmic thickening in the 

 micromere region as in the normal case. 11;25 AM. 



The same showing a very thin ectoplasmic layer over the cut surface. 

 11.4-) AM. 



Egg cut obliquely just above tlie " head." 11.22 AM. 

 Enucleated fragment of the same divided by a slightly curved cleavage 

 plane. 0.10 PIM. 



Egg cut a little above the " head."' 9.85 AM. " 



Enucleated fragment of the same showing a thick ectoplasmic accumulation 

 along the cut surface. Tlie nucleated part was at the four-cell stage. 

 10,55 AM. 



Egg cut horizontally a little above the " head." Notice the thickening of 

 the ectoplasm along the cut surface of the nucleated pieces. 2.40 Pm. 

 The " head " at a, 2.50 PM., and at b, 3.25 PM. 



Enucleated piece of the same. 4.40 PM. At G PM. tlie upper bridge 

 became broader. 



Enucleated fragment obtained by a horizontal cut (outline in dotted line) 

 10.2 AM. ; the same (in full line) 11.15 AM. In the beginning the " head " 

 came down at the rate of 18 ;« per minute, and stopped at the spot repre- 

 sented in the latter. 



Cleavage farrow and " head " of the same magnified XI 02. 11.15 AM. 

 Egg from which the right-hand nucleated portion has been cut off 

 horizontally. Irregular mass attached to the nucleated fragment is the 

 portion that flowed out. 10.45 AM. 

 The same. 11.27 AM. 



