54 MR. F. E. BEDDARD ON ZOLOSOMA TENEBRARUM. [Feb. 5, 
matter, after being liberated from the cells containing it, was treated 
with an alkali (ammonia and potash were used), it altered its colour 
into a fine reddish purple; this could be changed back again into a 
yellowish green by treatment with mineral acids. When the coloured 
cells were treated by an alkali in situ, their colour changed gradually 
to a dirty brown; they never exhibited the fine purple hue shown 
when the pigment was expelled from the cell. The pigment was 
dissolved by turpentine forming a gamboge-yellow solution, which 
soon faded; this could be converted into violet by alkali. These 
reactions appear to show that the green pigment in MHolosoma 
tenebrarum is not chlorophyll. 
It resembles, in fact, in the changes of colour produced by 
alkalis and acids, certain pigments described by Moseley (‘‘ On the 
Colouring-matters of various Animals, and especially of Deep-sea 
forms dredged by H.M.S. Challenger,” Quart. Journ. Micr. Sei. 
vol. xvii. 1877, p. 1) and other observers, and is possibly a member 
of that numerous class of pigments which serve a respiratory pur- 
pose. It is curious that the colour of the pigment, dirty green 
when acid, and purple when alkali, appears to be more like that of 
the perivisceral corpuscles of Spatangus purpureus, as described by 
Geddes (‘Observations sur le fluide périviscéral des Oursins,” * 
Arch. de Zool. Exp. t. viii. (1879), p. 483), than any other pigment 
of which I can find a description. In neither Bonel/ein nor Chloro- 
cruorin does there appear to be, judging from the papers of Sorby 
(‘On the Colouring-matter of Bonellia viridis,’ Quart. Journ. 
Mier. Sci. vol. xv. 1875, p. 169), Lankester (Journal of Anat. & 
Phys. vol. ii. and vol. iv. 1870), and MacMunn (“On the Chro- 
matology of the Blood of some Invertebrata,’ Quart. Journ. Micr. 
Sci. vol. xxv. 1885, p. 469), a change of colour exactly like that 
of the green pigment of Molosoma; and these are precisely the 
pigments which one would be, @ priori, disposed to compare with 
that of olosoma, sixce they are Annelid pigments. However, in 
the absence of spectroscopic data, it is impossible to make any 
comparisons of great value. 
Bonellein, which is a green pigment, is converted into violet by 
the action of acids; it evidently therefore differs materially from the 
pigment of Molosoma. According to MacMunn (loc. cit. p. 478), 
chlorocruorin, wheu treated with an alkali after rectified spirit, 
became yellowish. I could not obtain this reaction, as the alcohol 
decolorized olosoma tenebrarum*. 
The pigmented cells of Holosoma are by no means unlike those 
of Thysanozoon® (see Lang, “Die Polyclader,’”” Naples Monographs, 
1 This pigment appears to be Hchinochrom (see MacMunn, “ On the Chroma- 
tology of the Blood of some Invertebrates,” Quart. Journ. Micr. Sci. vol. xxv. 
(1885) p. 485. 
° There are other green pigments of course, about which, however, nothin 
appears to be known, except that in some cases (¢. g. those of Trocheta, Phyllo- 
doce) they yield no absorption-bands. 
8 While working at the Plymouth Biological Station in August 1888 I ob- 
served a Planarian with large green spots exactly like those of d¥olosoma (so 
