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Show 564 PBOF. F. J. BELL ON HOLOTHUROIDS. [Dec. 2, After treatment with strong hydrochloric acid the alcoholic solution becomes yellowish in reflected as well as in transmitted light : it becomes dirty yellow on the addition of ammonia, and throws down a turbid precipitate which gradually became more and more flocculent; this was at first of a dirty white colour, but became yellow on standing for a short time. Just as in the case of antedonin, the precipitate from the ammoniacal solution was very abundant, but, unlike it, the solution was much less strongly coloured after the deposition of the precipitate. After filtration the precipitate was left as a yellowish powder, which was insoluble in water or alcohol, but dissolved pretty readily in acidified alcohol; in this point it again resembles antedonin. After solution in acidified alcohol, the precipitate became of a faint yellow colour, but did not give a green reflection. Further addition of alkaline reagents to the filtered alcohol produced a further precipitate. On the whole, then, it is clear that there is in Holothuria nigra a colouring-matter of the same character as antedonin : but if the body now under consideration has distinctive absorption-bands, they are in the Cotton-Spinner obscured by another colouring-matter, which is especially richly deposited at the distal or attached end of the Cuvierian tubes, and which readily, after solution in alcohol, stains the human skin yellow. The viscera are at least as much as the integument the seat of the antedonin-like colouring-matter, for spirit which has only come into contact with the viscera is as distinctly yellow and green as is that in which the whole of the body is preserved. Here again, then, we have an example of that diffusion of colouring-matter through the tissues of an Echinoderm to which Prof. Moseley has, in the paper cited, already directed attention. The fact that the threads of the Cuvierian organs swelled out in water led me to try and see if I could detect the presence of mucin. No response, however, in that direction was given by the ordinary experiment of adding to the water, in which some tubes had been standing for more than ten days, solid chloride of sodium, nor did I get any precipitate with acetic acid. Shortly after death the threads are hardly at all sticky, but after a few days' treatment with strong salt solution they become much more so; the threads are quite well preserved from putrefaction, even in hot leather, by being placed in strong salt solution: a solution not carefully sheltered from atmospheric air harboured but few bacteria after being some ten weeks in a not over-clean room. If, however, the threads are left in sea-water or exposed to the air they rapidly undergo putrefaction, and give off a more offensive odour than any other decomposing animal substance with which I am acquainted. In one specimen forwarded to me the tubes had evidently been protruded in a natural manner : a compact strand of about an inch in length and one fifth of an inch in thickness protruded from the cloacal orifice ; this at its free end was frayed out into a large number of comparatively fine tubes which were attached to the seaweed in the water, and extended over about two inches in breadth. As I |