54 MR. F. E. BEDDARD ON jEOLOSOMA TENEBRARUM. [Feb. 5, 



matter, after being liberated from the cells containing it, was treated 

 with an alkah (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. Wlien 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 ^olosoma 

 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. Sci. 

 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 purpiireus, as described by 

 Geddes (" Observations sur le fluide perivisceral des Oursins," ' 

 Arch, de Zool. Exp. t. viii. (1879), p. 483), than any other pigment 

 of which I can find a description. In neither BoneUein nor Chloro- 

 cruorin does there appear to be, judging from the papers of Sorby 

 ("On the Colouring-matter of Bonellia viridis," Quart. Journ. 

 Micr. Sci. vol. xv. 1875, p. 169), Lankester (Journal of Anat. & 

 Phys. vol. ii. and vol. iv. 1870), and MacMunn ("OntheChro- 

 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 ^olosoma ; and these are precisely the 

 pigments which one would be, a priori, disposed to compare with 

 that of ^olosoma, since they are Annelid pigments. However, in 

 the absence of spectroscopic data, it is impossible to make any 

 comparisons of great value. 



BoneUein, 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), 

 chlorocruovin, when treated with an alkali after rectified spirit, 

 became yellowish. 1 could not obtain this reaction, as the alcohol 

 decolorized yEolosoma tenebrarum'. 



The pigmented cells of JEolosoma are by no means unlike those 

 of Thysanozoon' (see Lang, "Die Polyclader," Naples Monographs, 



' This pigment appears to be Echinoclirom (see MacMunn, " On the Chroma- 

 tology of the Blood of some Invertebrates," Quart. Journ. Micr. Sci. vol. xxv. 

 (1885) p. 483. 



- There are other green pigments of course, about which, however, nothing 

 appears to be known, except that in some cases (c. g. those of Trochafa, Vligllu- 

 doce) they yield no absorption-bands. 



^ While working at the Plymouth Biological Station in August 1888 I ob- 

 served a Planarian with large green spots exactly like those of A^olosumu (so 



