the number and diminishing the size of the cells, 

 presented another singular series of changes which 

 may be well worth mentioning here. These changes 

 concern the central transparent body within each 

 cell, properly called the "nucleus." Regardless 

 of in whatever light one may view the quidditative 

 force that urges onward this peculiarly mystifying 

 process of cell-division, the machinery through 

 which it operates is manifest. In every instance the 

 division of the cells was previously announced by 

 the behavior of this significant component. It be- 

 came altered in appearance and finally dissolved 

 from view to occur again only when division was 

 completed, itself now divided into two and each 

 half occupying a new-formed cell. 



Ten hours after the time of fertilization, exam- 

 ination of the serpent-star eggs showed that they 

 consisted of a spherical aggregation of compressed 

 cells, each containing a nucleus, surrounding a 

 hollow interior. The eggs were still invested with 

 their original membranous shells. 



But now came a complete and striking change. 

 And it is here that our echinoderm forges its first 

 links in that chain of embryological evidence 

 which so convincingly secures it to our Dipleurula 



[100] 



