Chlorocruorin and Hæmoglobin

Abstract

There are four respiratory pigments which circulate in the blood or are found in the body cavity of animals. Two of these, the red hæmoglobin and the dichroic red-green chlorocruorin, are close chemical relatives. Chlorocruorin is confined to certain marine polychæte worms and is characteristic of the group Serpulimorpha, comprising the families Serpulidæ and Sabellidæ. Hitherto it has been thought that all species in this group possess chlorocruorin in their blood. This, however, is not the case. I have found chlorocruorin in twenty-one species of the group, belonging to fifteen genera. One of the species with chlorocruorin is Spirorbis borealis Daudin, but another species of the same genus, namely, S. corrugatus (Montagu), has hæmoglobin as its blood pigment. Yet another, species, S. militaris (Claparéde), has neither pigment: its blood is colourless. That chlorocruorin and hæmoglobin are really absent here, not just dilute, is proved by the fact discovered by my colleague, Miss Jean Hanson, that the benzidine reaction is negative in the blood vessels of S. militaris. These several species of Spirorbis live in similar situations, so that the possession of either or neither respiratory pigment appears to be functionally unimportant.