56 MR. F. E. BEDDARD ON ZOLOSOMA TENEBRARUM. [Feb. 5, 
vations known to me upon the presence or absence of this colouring- 
matter in the blood of Holosoma. Lankester (“A Contribution to 
a Knowledge of the lower Annelids,” Trans. Linn. Soc. vol. XXVi. 
p- 642) has mentioned that the blood of &. ehrenbergii is pink ; 
but pink is not a colour which is associated with the presence of 
hemoglobin. With regard to the branched yellow cells described 
by Vejdovsky in the dorsal vessel of Holosoma, I would venture to 
suggest that they correspond with the peculiar glandular structure 
which occurs in the dorsal vessel of Céenodrilus and of many other 
Annelids?. In this case, the colouring-matter is probably not 
heemoglobin*. The absence, therefore, of a special respiratory pig- 
ment in Zolosoma 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 débris 
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 olosuma tenebrarum is related to the red pigment 
of 4. quaternarium and Al. ehrenbergii. 1 have applied the 
iodine test mentioned above to Z. variegatum, but did not sueceed 
in getting the black stain; the pigment of this species is of quite 
a different shade of green to that of 4. tenebrarum. 
EXPLANATION OF PLATE V. 
Molosoma 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 l'; Z, ciliated pit of the parent ; s, short sete of posterior 
segments. 
2. Coloured epidermic cells as seen before the use of reagents: 0, coloured 
oil-drop ; 2, nucleus. 
2a. Young coloured cell. 
3. Coloured epidermie cells after treatment with osmic acid: 2, nucleus ; 
p, cell-protoplasm forming a thin peripheral layer and rendered 
visible by shrinking of coloured oil-drop. 
4. Coloured epidermie cells after treatment with iodine solution. 
5. Débris of epidermie cells coloured violet on treatment with an alkali. 
6. Contents of coloured epidermie cells expelled by acid. 
7. Coloured epidermic cell showing shrinking of oil-body after treatment 
with osmie acid: 9, oil-globule; , nucleus; p, protoplasm. 
8. Sets: a, of ventral bundles of posterior segments; 2, transition between 
these and hair setz. 
1 See J. T. Cunningham, “On some points in the Anatomy of Polycheta,” 
Quart. Journ. Micr. Sci. vol. xxviii. p. 251, for an account of what is known of 
this organ in the Polycheta ; also Hisig, “ Die Capitelliden,” Naples Monographs, 
xy. pp. 691, 692. 
? Though possibly a derivative. 
