GREEN PIGMENT OP INTESTINAL WALL OP OH^TOPTBRUS. 449 



The result was the interesting and important paper by Mr. 

 Sorby published in this Journal in 1875, wherein he describes 

 the acid, neutral, and alkaline conditions of this pigment, 

 characterises it spectroscopically, and gives to it the name 

 " Bonellein." I shall take the liberty of changing that name 

 in the present paper to "Bonellin." 



Bonellin was subsequently studied by Krukenberg {' Vergl. 

 Physiol. Studien,' ii, 1882), and by Schenck (Sitzb. k. Akad. 

 Wiss. Wien,' 72, ii), who did not add anything material to 

 the observations published by Sorby. Krukenberg, indeed, 

 fell into some errors on the subject. 



After Sorby's demonstration of the independent and peculiar 

 nature of Bonellin, I was more than ever anxious to re-examine 

 the pigment of Chaetopterus, but more than twenty years have 

 elapsed before I have carried out my intention. 



In the meantime my friend and fellow-student Moseley 

 provided himself with a micro-spectroscope as part of his 

 equipment when he served as naturalist on the "Challenger" 

 Expedition, and he published on his return in this Journal 

 (vol. xvii, 1877) a very interesting account of a number of 

 colouring matters obtained from marine animals and exa- 

 mined by him with the spectroscope. One of the most 

 remarkable of these was a pigment from the integument of 

 species of Pentacrinus, which occurs in these animals in such 

 abundance that the spirit in which they are first preserved 

 becomes deeply impregnated with it, and will yield the pig- 

 ment as a powder on evaporation. 



Moseley gave the name Purple Pentacrinin to this substance. 

 He showed that its solution in alcohol was fluorescent, and, 

 like Bonellin, could be changed in colour accordingly as the 

 fluid was rendered alkaline or acid. It gave a very definite 

 set of three absorption bands, the position of which were fixed 

 and recorded in a spectrum map by Moseley. The colour 

 transmitted by the acid solution is "an intense pink," that by 

 the alkaline is bluish green, whilst the fluorescence is red. 

 A second equally striking colouring matter was called A ntedonin 

 by Moseley, and found by him in deep-sea species of Antedon 



