448 E. RAY LANKBSTER. 



other organic pigments. I satisfied myself that the pigment 

 derived from Chsetopterus was in no way connected with the 

 lodgment of particles of green vegetable matter in its alimen- 

 tary canal, but was due to a strong and abundant blackish- 

 green substance formed in the actual walls of the middle 

 portion of the alimentary tract of the Chsetopterus. I sup- 

 posed that this substance, on account of its solubility, fluores- 

 cence, and banded absorption spectrum, must be considered as 

 a ' variety' or ' species' of " chlorophyll.'' 



In 1872 I obtained at Naples specimens of the Gephyrean 

 Bonellia viridis, and was extremely interested to find that 

 they — like Cheetopterus — imparted a strong greenish colour to 

 the alcohol in which they were placed, accompanied by fluores- 

 cence. 



This coloured solution I found also gave a very powerful 

 series of absorption bands when examined with the spectro- 

 scope, and I erroneously concluded that this colouring matter 

 too — from Bonellia — must be considered as a " chlorophylloid" 

 substance. 



In the first and second editions of the English translation of 

 Sach's 'Botany' (Oxford, second edition, 1882, p. 767) a note 

 is published in which, on my authority, it is stated that '^ a 

 chlorophylloid substance" occurs in the intestinal wall of 

 Chsetopterus and in the integument of Bonellia. 



I had observed that the absorption spectrum of the colouring 

 matter of Bonellia, though resembling that of chlorophyll, yet 

 differed considerably from it, and I proposed to myself to make 

 a more careful examination both of it and of the green pig- 

 ment from Chsetopterus, with the use of adequate measuring 

 apparatus and scale in fixing the position of the bands in their 

 absorption spectra. 



I was prevented from carrying out my purpose by the loss 

 of my Chsetopterus material and the difficulty of obtaining 

 more, and by the pressure of other pieces of work. 



It fortunately occurred to me in 1875 to ask my friend Mr. 

 H. C. Sorby, F.R.S., to undertake the investigation of the 

 colouring matter of Bonellia, of which I had a certain quantity. 



