| OCR Text |
Show 56 MR. F. E. BEDDARD ON JEOLOSOMA TENEBRARUM. [Feb. 5, vations known to me upon the presence or absence of this colouring-matter in the blood of JEolosoma. Lankester ("A Contribution to a Knowledge of the lower Annelids," Trans. Linn. Soc. vol. xxvi. p. 642) has mentioned that the blood of JE. ehrenbergii is pink; but pink is not a colour which is associated with the presence of haemoglobin. With regard to the branched yellow cells described by Vejdovsky in the dorsal vessel of JEolosoma, I would venture to suggest that they correspond with the peculiar glandular structure which occurs in the dorsal vessel of Ctenodrilus and of many other Annelids \ In this case, the colouring-matter is probably not haemoglobin \ The absence, therefore, of a special respiratory pigment in JEolosoma renders it more possible that the pigment of the integumental glands may perform that function. I imagine, from my observation of the living worm, that the pigment may also have a protective value. When a number of the worms are placed in a watch-glass with some of the vegetable debris upon which they feed, they are seen to hide themselves in this ; the general colour of the worm is a faint brownish, which harmonizes very well with the colour of the substances upon which they feed and among which they live. When the worm is magnified these resemblances are hardly obscured ; the worm is not unlike a slender stalk of some plant in which there are only fragments here and there of yellowish chlorophyll. It will be of interest to inquire how far the pigment of JEolosoma tenebrarum is related to the red pigment of JE. quaternarium and JE. ehrenbergii. I have applied the iodine test mentioned above to JE. variegatum, but did not succeed in getting the black stain ; the pigment of this species is of quite a different shade of green to that of JE. tenebrarum. EXPLANATION OF PLATE V. JEolosoma tenebrarum. Fig. 1. A n individual, from the ventral surface, with a young bud in course of formation: pr, ciliated prostomium of the young ; the lateral ciliated pit is seen at V; I, ciliated pit of the parent; s, short sette of posterior segments. 2. Coloured epidermic cells as seen before the use of reagents: o, coloured oil-drop; n, nucleus. 2 a. Young coloured cell. 3. Coloured epidermic cells after treatment with osmic acid : n, nucleus; p, cell-protoplasm forming a thin peripheral layer and rendered visible by shrinking of coloured oil-drop. 4. Coloured epidermic cells after treatment with iodine solution. .5. Debris of epidermic cells coloured violet on treatment with an alkali. (>. Contents of coloured epidermic cells expelled by acid. 7. Coloured epidermic cell showing shrinking of oil-body after treatment with osmic acid: o, oil-globule ; n, nucleus ; p, protoplasm. 8. Seta;: a, of ventral bundles of posterior segments; b, transition between these and hair setse. 1 See J. T. Cunningham, " O n some points in the Anatomy of Potycheeta " Quart. Journ. Micr. Sci. vol. xxviii. p. 251, for an account of what is known of this organ in the Potycheeta ; also Eisig, " Die Capitelliden," Naples Mono°*raphs xv. pp. 691, 692. & *• .f »> 2 Though possibly a derivative. |
