382 



Dr. C. A. MacMunn. 



It was difficult to get the reading of the second hsematin band, but the 

 first extended from X568'5 — 559'5 ;* the band at F after dilution with 

 water seemed to extend from \509 — 484. On exposure to the air 

 the ha?matin bands faded away, but were again brought back with 

 sulphide of ammonium, more distinctly than before. (Sp. 13.) An 

 alcohol extract of the liver showed only some shading at F, and no 

 band could, be seen in red, either before or after the addition of nitric 

 acid. 



ECHINODERMATA. 



In this sub-kingdom I have as yet only examined starfishes and 

 specimens of Echinus. 



Uraster rubeus. — The radial, pyloric, or arborescent cceca of starfishes 

 are supposed, I believe, by some to function as a " liver," while others 

 suppose they are of respiratory significance. According to the 

 following observations they do function as the so-called liver of other 

 invertebrate animals, i.e., they — in addition to their probable use in 

 preparing a digestive ferment — serve as organs for the storing, and 

 probably the actual production, of pigments for surface coloration. 

 This at least is the conclusion which spectroscopic study of their 

 colouring-matters suggests. 



In different specimens pigments of a different character occur which 

 seem to have a close connexion with those of the integument. 



The alcohol extract of the radial coeca of one specimen (the integu- 

 ment of which had a red colour, and which was found to be due mainly 

 to tetronerythrin with probably a small amount of a pigment giving 

 the spectrum and having the negative insoluble characters of Moseley's 

 actiniochrome) was after filtration a fine orange colour, and showed 

 the peculiar absorptive property of tetronerythrin. f 



Another specimen had brown radial cceca interspersed with green, 

 the alcohol extract was yellow and gave a band in red and one just 

 before D ; the first extended from X666 — 639, and therefore was 

 slightly nearer the violet end of the spectrum than in the case of the 

 enterochlorophyll of other invertebrate animals already referred to. 

 The whole of the violet end of the spectrum was shaded up to three- 

 fourths the distance from D to E. The latter shading was cleared up 

 by nitric acid which did not remove the other bands. % In a shallow 



* The second just before E (see sp. 13), for although it could not be measured 

 by means of the chemical spectroscope it was well seen in the microspectroscope. 



f Hoppe-Seyler, " Handbuch Physiol, u. Pathol. Chem. Analyse," 4th ed., 

 p. 220. This pigment is present in Homarus, Cancer, Carcinus, and Astacus, as I 

 have found it in the shells of all of them. (Cf . Merejkowski, quoted in " Nature," 

 Jan. 19, 1882.) 



X Probably owing to presence of tetronerythrin, the colour of which is destroyed 

 by nitric acid. 



