PERIVISCERAL FLUID OF ECHIXODERMS. J.U 



leucocytes, thus supporting Goodrich's assumption. Theel 

 ('21), however, in a review of his descriptions of the types of 

 amoebocytes in the perivi-ceral fluid of Asterias nibens and Pare- 

 chitius miliaris, states that he distinguished two types of amcebo- 



es in the coelomic cavity of these forms, the "white or hyaline 

 plasma-amceboc} -M<\ the "bladder amoebocy These 



description- were n< e<l to by Goodrich nor myself althov 



they a; if to both of our papers. A< cording 



Nieel the i\vn type- "l aincebocytes are very dissimilar, the 



" ill. i'l' NT ami i -I" 'not being flattened nor spread out on the 



stirfa< e 1*1 the ;Jass when a drop of the fluid is placed on a glass 



slide, but remaining thick and compact with the bladder lying in 



ml superimpo-ed l. : \ers. On the other hand, the "hyaline 



ma-ami ' " in the fresh fluid are characteri/ed by the 



;<>n of : cell body with longer or shorter 



ido| l( idi.i. I \presses doubt as to whether or not one 



type mav be < ! fmin the other. Following the terminol. 



1 by ('.oodrirh. I ,nn calling the cells with the membranous 

 llap^ leucocytes, and regarding Theel's "hyaline pla-ma-amoebo- 



;se of the leucocytes from my ol^er\M- 



tion-..n the formation of syncytia. Theel ('21 in e\pre--in^ r an 

 opinion as to tin- possibility of morphological changes in such 

 celN BS H it may be presumed that the character of 



tin- MiiTMiindin.; meiliiim may play an important part in that, 

 and abo\e all mo\i-ment .md relative stillness, the former ]>re- 

 ventin^ ami tlu- latter forwarding the pro i tran-mntation. 



It" for in-ianer .Hi .im.i-bocyte leaves the ci-luinic cavity in onl r 

 to immigrate into tin- tiues of the bod\- wall, it mu-t n& ess irily 

 tinl<-r^. < .-Main rh.m^es of form. When a cell passes over from a 

 pa i\ e drift to an aetive motion, its primitive globular eonhyura- 

 tion mn-t be exch inged for another ami accommodated to creep- 



ilU about. " 



Therefore, thi nee of two fc.rms of cells in the freshly 



drawn drop doe- imt i neee--ity mean that because of this 

 occurrence u e are -I- ilin^ with two distinct types instead of an 

 active and pa i\c form of one type of cell. It is reasonable to 

 suppose that these cell- have a cycle of life and that as they be- 

 come older this change to a more passive condition leads to a 

 change in form. Since the activities of these cells are comparable 



