Hydroid Pigments. I. General discussion and pigments of the Sertulariidæ

Abstract

1. The yellow colours of the hydroids include at least two groups, the carotinoids found in the Antennulariidæ and Haliciidæ and the flavone-like pigments that occur in the Sertulariidæ. From the literature a third group, the uradines, may be added.2. The flavone pigments and their relatives are all water soluble and are thus distinguished from the carotinoids which are not water soluble, but may be dissolved in the usual fat solvents.3. In the Sertulariidæ studied, a graded series of chromatophore groups and pigments was found which ranged from the colourless speciesSertularia argenteaEllis and Solander, through the yellow ofSertularella gayiLamaroux andS. polyzoniasLinnæus, to the orange-brown ofThuiaria articulataPallas. The brown ofSertularia pumilais probably also a flavone derivative.4. The flavones and related pigments occur extensively in the plant kingdom. It is probable that the flavone-like pigments found in the Sertulariidæ are of plant origin.