15. The flat, ST^rend out -osition of the cells nt once 

 suggests the idea thit the eg?^ "lay have been subjected to 

 nressure, -ted This r^ight have been the case if the eggs 

 had been studied on a slide under a cover glassj but there 

 is no evidence that pressure was the cause of this nlate- 

 lil:e arrange'-ent , for these forrs v/ere occasionally found 

 arcng a variety of othe- forir.s '.vhile studying the living eggs 

 in a sr-all preraratior dish in sea-vater with a two-thirds 

 ob.iective. As the eggs nresent a number of different forms 

 when subjected to the same external ■onditions, it see-s 

 that the cause of these differences rust be sought in the 

 nature of the egg itself rather than in any surrounding 

 influences . 



The later cleavages follov; at intervals of about the 

 saT:e duration as in the ^receding stagjes. The irregularities 

 of arrangement of the blastoreres increase as the cells be- 

 cone riore numerous. On account of the smallness of the 

 blastomeres and the extreme ODacity of the oPf,, it becomes 

 imnossible to follow the segmentation in detail a-^y further. 



