(77) 

 tion t:e ulooa ecrruscle masses occupv in one fully fonneu Ac- 

 tinctroc'ia, 



1 have secLionea some lo or 20 larvae with 12 or 14 tenta- 

 cles and with one exception I have found that when tne mesodermal 

 masses are present on the ventral body v/all, tiiare are no blood 

 corpuscle masses present in che larva ana that when the bloou 

 corpuscle masses are present, ti.ere are no mesodermal iiiasses. 

 In the excer.tiov- which 1 have mentionea, small ulood corpuscle 

 jaasses were found applied to the stomach wall and masses of 

 cells bilaterally placed v/ere found on the ventral somatic wall 

 but these cells had already taken on the character of blooa 

 CO rpuscles, 



Ikeda (9) has described a "irieso bias tic cell mass" viiich he 

 evidently considers as givin.; rise to tne aaulL boay cavity and 

 its position is verj similar to that of the laeso bias tic masses 

 that 1 have described above. They are both products o'*'" ti.e mes- 

 oblastic lining- of the ventral somatic '.vail and are situatea be- 

 tween thiC plane of the bases of the teiitacles and the plane of 

 the somatic ii.'sertion of the mesentery betv/een the collar axid 

 trunk, Althouc^h Ikeaa aoes not touch upon the very early ori- 

 ,,ij' 0"!' the adult boay cavity yet it seems probable that h.e con- 

 siders i t as arisin^^ from a sinj,;le mass of cells. The meso- 

 blastic masses that 1 have described above are paired and b-i- 



