356 JOHN F. FULTON, JR. 



and into this the round red granules subsequently flow. The 

 conformation of the pseudopodia resembles closely that 

 described by Goodrich (1919) for the coelomic corpuscles of 

 Asterias glacialis. Thus (as first shown by Geddes, 

 1880) the cell is truly amoeboid, being able both to protrude 

 and to withdraw its pseudopodia. 



It seemed a curious fact that the cells within the body-fluid 

 of the sea-urchin should be of identically the same colour as 

 the pigment granules which give to the animal its characteristic 

 coloration. Consequently an effort was made to determine 

 whether or not the two pigments are identical. The same 

 technique was employed as was made use of in settling the 

 identity of the pigments from A. bermudensis and 

 C. passiflora (p. 347), viz. that of testing their action in 

 the presence of certain solvents, and the results seemed to 

 indicate clearly that the two pigments are one and the same. 

 In examining the external pigmentation, small pieces of the 

 tube-feet were employed, since the behaviour of their coloured 

 granules can be watched much more closely than can those of 

 the spines. For testing the perivisceral fluid, fresh smears were 

 used to which the reagents were added with a capillary pipette 

 while under observation. Of the alcohols, amjd was the only 

 one which dissolved the pigments, they being very readily 

 soluble, however, in this reagent. Neither of the pigments were 

 extracted by the lipochrome solvents, ether, chloroform, petro- 

 leum ether, or xylol. The colouring-matters are readily 

 dissolved by 10/N solutions of the acids, dissolving \^-ith particu- 

 larly great rapidity in valeric acid.^ In the presence of alkalis 

 both pigments w^ere darkened, but not extracted. 



After these experiments had been made, it came to the 

 author's attention that Geddes, in a personal communication 

 to Gamgee (1880, p. 134), stated his belief that the pigment 

 of the red amoeboid cells was identical (in Echinus) with that 

 of the epidermal spines. This view resulted from a very thorough 

 study of the body-fluid of sea-urchins (Geddes, 1880). Con- 



^ This again corroborates Crozier's (1916 rt) conclusion that valeric is 

 the most penetrating of all acids. 



