﻿duerden] morphology of coral polyps ioi 



represented by a thin homogeneous layer, which has been regarded 

 as a skeletal membrane, coming between the actual polypal tissues 

 and the corallum. 



The synapticula, which art 1 solid calcareous bars, uniting adjacent 

 septa across an interseptal loculus, are found actually to perforate the 

 skeletotrophic tissues lining the two walls of the loculus, and also any 

 mesentery which may he included within the loculus. Recently they 

 have been described as originating from independent continuous 

 upgrowths of the basal disk, but the anatomy of the polyps gives no 

 support for this conception. 



ASEXUAL REPRODUCTION 



Vegetative or asexual increase assumes a great importance in the 

 growth of corals, resulting in the production of colonies or stocks, 

 often of large size and complexity of form. Yet, however diverse 

 in form the colonies may become, their origin can be reduced to two 

 sharply-defined processes, namely, budding and fission. Many varie- 

 ties of both types of increase have been studied, and reveal that the 

 resulting colonies are characterized by morphological differences of 

 much significance. 



Budding or gemmation may take place from almost any part of 

 the polypal wall, and in every case the buds are found to reproduce 

 all the characteristics of the larval polyp. The mesenteries, tentacles, 

 and septa display a cyclic hexamerism, and two pairs of directives 

 occur. Also in the course of their development the organs in buds 

 pass through practically the same stages as in polyps reared directly 

 from larvae. Hence it follows that coral polyps arising by gemmation 

 are to be regarded as new and distinct individuals, just as much as 

 polyps originating by sexual means. 



It is otherwise where a colony increases by fissiparity. The process 

 has been traced in Manic ma areolata (Linn.) and Favia fragum 

 (Esper) from the larva, through the simple polyp, until fission is 

 fully established, leading to a complex polyp. The diagrammatic 

 figures 14 and 15, with their explanation, fully illustrate the stages 

 in Manicina. While yet simple, the polyp presents all the characters 

 of an ordinary cyclic hexameral species, including the presence of two 

 pairs of directives. The first act of fission divides the stomodaaum 

 into practically equal parts, each with half the original number of 

 complete mesenteries attached to it, and including, of course, only 

 one pair of directives. The number of mesenteries increases with the 

 growth of the fission polyp, and the hitherto incomplete pairs become 

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