PERTVISCERAL FLUID OF ECHIXODERMS. 245 



pigment from food, it may be that they are the descendants of 

 the pigmented cells (chromatophores) of the larval Echinoidea. 

 These cells are present in the segmentation cavity of the larval 

 Echinoids, but I have not found any reference as to their occur- 

 rence in the larva? of other classes. If this is true, then we are 

 dealing with an amoel" which is specific in the Echinoidea 



and may yet be found lo be derived from the colored -ub-t.mce- 

 characu-ri-tic of the Kchinoid ovum. 



;. ".V .). 30. 



- 



,. (' 



" Amu 1 \\ itii colnrle les" (1 re more 



widely di-tribuied in the Kchim -derm- lli.in tin- pum -uted ones 

 .ind are loimd in the < )phiuroidea. lu'lnnoidi-.i .uid llolotlm- 

 roidc.i. "riu-frll^of tin- i\ [r ,irr much mmv abundant and .iriivi- 

 in the I lolotliiiroidi-.i than in thr other classes. Th.-y an- al-o 

 much lr >tabk-aud i li~inti-^raic -01 >n after withdrawal from tin- 



bod\-. Tlu-x arc drr|ily stained b>' nu-tlu'lene blur--ea\vatri- or 

 iH-uiral red--ra\\aH-r -olution- ction \vhich i- not i haractcr- 



istic of the "amoeb with colorle-- -plu-ruli--" in the other 



classes. 



It is to be noted that the -i/.- of the >pherule~ i- constant for 

 any i;i\ en amd'oc\ ie, but that there is a X'ariatioii in the H/e- of 

 the spherules of amoebocyte- characteristic <pf dilti-rent animal-. 

 Theel has also remarked upon this and ha- pointed out tli.tt the 

 "amocbocytes with colorless spherules" predominate in the 

 I lolothuroidea which he studied. He says: "In the holotlmrid- 

 the white corpuscle- an- thoroughly predominant, though, tl 



