DR. C. A. MAC MUNX ON THE CHROMATOLOGY OF ACTINIAE. 
659 
distributed in the animal kingdom, and which I have called histohcematins or tissue 
hsematins, so that the biliverdin may in that case also be looked upon as excretory, 
and at the same time useful for decorative purposes. 
A similar instance of a used-up pigment being got rid of in the integument is the 
occurrence of haematoporphyrin in the integument of starfishes and slugs, as I have 
proved. # This colouring matter can be extracted by digesting the integument in 
the cold for some hours in alcohol acididated with sulphuric acid, and it can be easily 
shown that it is present in the state of haematoporphyrin as such. The presence 
again of enterohaematin in the “ bile ” of pulmonate mollusks, in that of the crayfish, 
and in that of Patella vulgaris, as I have lately found, and of histohaematins in 
various parts of their bodies, is a parallel instance of the presence of an immature 
respiratory pigment or pigments taking the place of the haematin-yielding pigment in 
the Actiniae. The latter cannot, however, be looked upon as a colouring matter 
intended to carry oxygen, but rather to Iceep it in combination until it is wanted by 
the cells for purposes of metabolism. As it is distributed all over the surface of some 
Actiniae, the whole body of such an animal may, in a physiological as well as in a 
morphological sense, be considered comparable to a single organ of a higher animal, so 
far, at least, as internal t respiration is concerned. 
In Sagartia parasitica the haematin-yielding pigment is replaced by a special one,| 
as already referred to, and in every species of Actiniae, even in those almost destitute 
of colour, the presence of respiratory pigments has been detected. 
In Anthea cereus, Sagartia bellis, and Bunodes ballii the same colouring matter is 
present not only in the tentacles but in other parts, and from the observations 
recorded in this paper, it is quite clear that all the chlorophylloid colouring matter in 
these three species is entirely due to the presence of “ yellow cells.” It is not within 
the scope of this paper to enter on a discussion of the nature of these “ yellow cells,” 
it will be sufficient to call attention to the facts that whenever present they have been 
found to possess a cellulose wall and to contain starch. This is in favour of the view 
held by Geddes,§ Brandt, the Hertwigs, and others, that they are of a vegetable 
nature, and are symbiotic algse. Another point in favour of this view is the behaviour 
of their solutions with caustic potash and soda, which, as I have already stated, dis¬ 
tinguishes them from animal chlorophyll and ordinary chlorophyll (of green land 
plants). The colouring matter itself, as Dr. Sorby and Professor Lankester || show 
* Proc. Birm. Philos. Soc., vol. iii., pp. 378 et seq. Another very suggestive connexion between 
biliverdin and hiematoporphyrin is furnished by the fact discovered by Sorby, namely, that these pigments 
occur in birds’ eggs. I have also found hasmatoporphyrin in the integument of the earth-worm. 
f I.e., tissue respiration. t In the ectoderm, see above. 
§ See ‘Nature,’ January, 1882, for Geddes’s paper and the subsequent letters of Professors Moseley 
and E. P. Wright as to Brandt’s priority, also P. Geddes’s reply. 
|| See list of chlorophyll containing animals drawn up by Professor Lankester, for 2nd English edition 
of Sachs’s ‘ Botany ;’ also his paper “ On Chlorophyll Corpuscles and Amyloid Deposits of Spongilla and 
Hydra,” Quart. Journ. Micro. Soc., vol. xxii., p. 229, &c,; also note to page 650, supra. 
