(It) 



batieri stvdiea aiia figurea by Roisle (£0) end ti.ose o ^' Phorou- 

 is d'Helt-^olana -^'itnired by Loi^t,, champs (1£). 



The foniiatioii o ""^ the mesocierm begins ii. Phoronis architeota 

 as sooii as ti-.o flatteried siae of the blastula bejj:ina to i-,astru- 

 late. In a fev; cases, rouna blastulae aro fouria, wi ti:in Ij:o 

 blastocoel of v;hich, are rati;er lart.;o i^ranular ar.herical boaicy 

 mvch larj^er than tie plasKiic corpuscles aescribea above. Each 

 o"^ these contains sx. o^a-'j^ve body wiach takes saffraxiin stain 

 ••i^-'iti. re>aainess. A comparison of these bodies witn the nuclei 

 of ti.e cells of the blastula wall convinces one at once that 

 they are not nuclei. In i^i;^, 14(a) ^ btc-^jcn tij"out,h such a 

 blastula is si.OvVix iii '.vhici: these bodies are seen vathiii the wall 

 of tne blastula as v/ell a.s insjae the blastocoel. ThiCy are iiri- 

 bcddcd in the v/ali v.ithout reference to tr.e liiui ts of tiie cell 

 aiid usually occupy the v/idth of two cells. Tne cells ei.closin^ 

 these peculiar bodies do not aiffer from tna cells surrounding' 

 them in that re^^ion ano eacn has its own nucleus. These bodies 

 are not the cut e^.ds of amoeboia processes which Calawell (5a) 

 and Roule (£0) observed, for such processes ao not occur in tne 

 blastulae of Piioronis architecta. I am unable to make any pos- 

 itive statement as to their- fate but it is ve^-y probable tx.at 

 they break up into the smaller plasmie cor^usclea. Sucn boa- 

 les as tne former mi^^nt easily be mistaKon for mesoderm cells 



