(75) 



f atioiis become ti.e t entacniar vesciela cf the aault. Thi.ti coi- 

 dJtion is aho'.vn very plaiiily iii a aorso-lateral Bcction o J" the 

 ActiiiG trocha Species, A. ("Fif^.oO) 



Blood Corpuscles aijd Their Ori gin; - E.B. ?/ilsori (24) has 

 tou.cheu upon the oritjin of the blooa corpuscles ana accoraint; 

 to him, the blood corpuscles uevelop in soli-a masses aai:crinj_: to 

 the stomach walls near the base of th.e tentacles. 



Caldwell (2) finds that the corpuscle masses "arise from 

 the mesoblast cells in front of the septum" but he has no thixig 

 :^urther to say about their position or origin, 



Ikeda (9) aescribes the blooa corpuscles as arising, from 

 "gigantic mesoblast cells in the body cavity of the larvae witii 

 one or two ^loiirt, of tentacles". Since the publication of tnis 

 aper, Ikeda has re^^ect^.d ti.io view although he has published 

 c thing en the subject, 



Menon (17) thinks that the blooa corpuscles arise -from the 

 splancnnoplpure covering the sto'.nach and its diverticulum. 



Accoraing to Cori (4), the blooa cor^ubcles in the adult 

 are formed from tne endothelium of the blooa vessels. 



In the Actinotrocha Species, A,, (probably that of Phoronis 

 architecta) the blood corpuscles usually make their appearance 

 aurin. the l4 tentacle stage, as in "Type A" aescribed by Ikeaa, 

 although I have founa larvae of this stage in v;hich definite 



