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 ^olosoma. Lankester (" A Contribution to 

 a Knowledge of the lower Annelids," Trans. Linn. Soc. vol. xxvi. 

 p. 642) has mentioned that the blood of ^. ehrenhergii 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 ^olosoma, 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 pig- 

 ment in ^olosoma renders it more possible that the pigment of the 

 integumental glands may perform that function. 



1 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 ^olosoma tenebrarum is related to the red pigment 

 of JE. quaternarium and ^. ehrenbergii. I have applied the 

 iodine test mentioned above to zE. varieyatum, but did not succeed 

 in getting the black stain ; the pigment of this species is of quite 

 a different shade of green to that oi M. tenebrarum. 



EXPLAJfATION OF PLATE V. 



Mohsoma tenebrarum. 

 Fig. 1. An 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 ; /, cilialed pit of the parent ; i«, short setje 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 eijidermic cells after treatment with osmic acid : ?;, nucleus; 



p, cell-protoplasm forming a tliin 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. 

 0. 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 ; «, nucleus ; p, protoplasm. 



8. Setae : a, of ventral bundles of posterior segments : h, transition between 



these and hair setie. 



See J. T. Cunningham, " On some points in the Anatomy of Polychceta" 

 Quart. Journ. Micr. Sei. vol. xxviii. p. 251, for an account of what is known of 

 this organ in the Volychmta ; also Eisig, '• Die Capitelliden,' Naples Monographs 

 XV. pp. 691, 092. ' 



^ Though possibly a derivative. 



