The Study of Corals

Abstract

THE existing corals are the most unsatisfactory group of the animal kingdom from a system atic point of view. They are accursed in that they have supposed ancestors and relations so far back as the early Cambrian, the play of stratigraphers, who care not for life. Their most prominent feature is an exo-skeleton of carbonate of lime, which is neither for protection nor for muscular attach ments, both of which are reflected in those of vertebrates and arthropods. There are radiating plates (septa) from centres, over which lie the mouths (stomodosa) of the anemones (polyps) that are seated upon them. Other structures are central columns (columella) and surrounding walls, all free edges toothed perhaps, and the skeleton (corallum) goes on perpetually thickening so long as the anemones live. There is immense variation in the size and height of septal teeth, and the septa vary in length, height, and thickness, as do all other structures, in correlation with rapidity of growth, with incidence of light, with water movements, and so on. Systematy becomes worse in ‘colonial’ or many mouthed or polyped forms, for these show in addition, more clearly correlated with environ ment, variation in the position and rate of pro duction of new polyps such as to give wide differ ences in the coralla. All modern reef builders have algae living and reproducing within their polyps, and these we judge to be the most important factor in their nutrition. They, like the chlorophyll in the tree, may produce vast modifications in the growth form of their host. Catalogue of the Madreporarian Corals in the British Museum (Natural History). Vol. 7: A Monograph of the recent Meandroid Astro. By Prof. George Matthai. Pp. v + 288 + 72 plates. (London: British Museum (Natural History), 1928.) n.p.