CONTRIBUTIONS TO ANIMAL CHROMATOLOGY. 91 
plants, e. g. in carrots, tomatoes, and Spanish pepper ; in fungi, 
such as Polyporus sulfuraceus, Peziza aurantiaca, 
Agaricus furfuraceus, and in a red alga Chlamydo- 
coccus pluvialis, &c. Those who are acquainted with the 
work of Sorby ! on vegetable colouring matters, cannot fail to 
see that among plants very different colouring matters have 
been here confused together under the name tetronerythrin by 
Merejkowsky. Of carrotin I‘shall have more to say further 
on, but no one ought to confuse this with the pigment of 
Peziza aurantiacus the ‘“‘ Peziza xanthine” of Sorby. 
In tomatoes I can find no tetronerythrin, and on the whole its 
occurrence among plants is very doubtful. It has evidently, 
therefore, been confused there with other yellow and reddish 
lipochromes. 
The same remark applies toits distribution among animals ; 
for although we come upon a pigment here and there, as, for 
example, among the Sponges, Starfishes, and Crustaceans, &c., 
which does answer to the description of tetronerythrin, yet in 
others the supposed tetronerythrin is found, on more careful 
examination, to be slightly different from it. If the description 
of tetronerythrin given by Merejkowsky be compared with that 
of the lipochromes, considered not individually but as a class, it 
will be found that it applies to almost any lipochrome. As pig- 
ments related to tetronerythrin, Merejkowsky included some 
which are soluble in water, but which by chemical or physio- 
logical means can be changed into tetronerythrin; thus by 
adding a drop of acid or caustic alkali, alcohol, or warm- 
ing to near the boiling point. So that many blue, grey, 
brown, and other coloured pigments change to orange red and 
then become insoluble in water, and soluble in such solvents 
as alcohol, ether, chloroform, turpentine, and acetic acid. 
Such are named by Merejkowsky, velelline, echinastrine, 
astroviridine, astrogriséine, ophiurine, and _astroviolettine ; 
while others which cannot be thus changed he names 
suberitine, astroidine, pelageine, chrysaorine, rhizostomine, 
echinorubine and echinine. But it is impossible to say what 
1 «Proc. Roy. Soc.,’ No. 146, vol. xxi, 1873, &. 
