In the year 1864 I obtained specimens of Chætopterus variopedatus, Renier (at that time called C. insignis by Baird), when collecting at Herm in the Channel Islands.
My specimens preserved in alcohol gave to the spirit a strong blackish-brown coloration, and the fluid was observed to have a deep red fluorescence. I showed the coloured fluid to Professor Stokes, of Cambridge, where in 1864 I was an undergraduate, and he rapidly examined it with a direct-vision spectroscope. He pointed out to me the remarkable absorption bands which the fluid caused in the spectrum of light passed through it, and expressed the opinion that these were similar to if not identical with those caused by some solutions of chlorophyll. In view of the fact that the colouring matter was soluble in alcohol and caused a red fluorescence, as well as a banded absorption spectrum resembling that of chlorophyll, Professor Stokes was...
