blastoineres. The aivisicii takes placo rather irre£ularly but 

 tixe blastomeros are all about of the saiQe siiie. 



The so-callea "biastocuel pore" observed by Ikeaa (9) 

 1 have also found o ccaaioiialiy in youn^ blastulae but I aw in- 

 clined to think tiiat it does not appear in a definite place 

 and that it is variable in occurrence, (■Pit;,s. lii-13) 



Two i.ours after the first cleavaj^s the blastula is com- 

 posed of seventy or eighty cells and it is still enclosed in 

 the egg membrane, 



'P'our hours later the membrane disappears ana the ciliatea 

 blastula begins to swim, (Fii^.l4) 



The blastomeres v/ere so muci: alike -and so uniforn in si^e 

 that I was not able to trace tneir individual nistory. It 

 vrould seem probable from Mas term an' s y/ork on Phoronia Euskii 

 (16) that the cell lineage migi-,t be follov/ed in that fb na, -^or 

 lie finas considerable difference in the size o ■*' the blasto- 

 meres in the early stages of" cleavaa,e at least, 



Tlie apical pole of the ciliatea blastula is provided v;i th 

 long cilia, ("fig, 14) The nuclei are situatoa nearer tlie out- 

 er ti:ari the inner surface anu tne inner ends of ti.e cells are 

 filled with rather aense ^^ranules. In the segmentation cav- 

 ity are ^ound tiie so-called "corpuscles", which have been ob- 

 served by most investigators working on the early stages of 



