LIFE-PROCESSES OF CORAL COLONY 115 



the destroyed area is very like that previously described as 

 occurring in those corals that grow like the massive forms of 

 Porites. 



The first step is the active marginal growth and the 

 formation of an excessive quantity of new material, which, in 

 the form experimented on {Madrepora pidchra), is at first of a 

 light blue colour, and is semi-transparent. In this new 

 material the mouths of corallites soon appear, and the edges 

 become covered by a host of uniform zooids, which soon spread 

 over the entire area destroyed by the injury, provided that the 

 area is not too large, and that no alga settles on it in the 

 meanwhile. It may be stated here that in experimental 

 injury, many experiments fail for the reason that the destroyed 

 or injured area commonly becomes a focus for the invasion of 

 boring parasites, Avorms, molluscs, sponges, and algse, and the 

 pure results of injury and repair become complicated. 



Where no such complication existed, areas of 5 by 5 

 millimetres, 20 by 8 mm., 20 by 10 mm., and 25 by 12 mm., 

 were completely covered by new material with a multitude 

 of new zooids in the course of 100 days, whilst larger areas 

 were commonly attacked by sponges or algse before repair was 

 completed. Yery much the same process is seen to occur 

 when constricting metal bands are placed round branches. 

 The zooids, where the bands exert their pressure, are destroyed, 

 and the general growth of the branch and the sympathetic 

 activity of the zooids at the margin of the injury soon tend 

 to cause the band to sink into the substance of the coral, 

 and to become completely embedded beneath the surface. 



It was previously stated that the type of repair naturally 

 tends to follow the type of growth of the injured colony ; and 

 this is generally true. If a coral has a particular mode of 

 growth, and if it be in such an environment that its mode of 

 growth is the one most suitable, then an injury is repaired or 

 a part regenerated on the same type of growth as that of the 

 colony. But the particular form in which a colony may be 

 growing may not be the form best suited for successfully 

 flourishing in that particular environment ; and then, following 



