Observations upon the Growth-rate and Oecology of Gorgonians. 87 



On the reef where the measurements previously mentioned were made, 

 a considerable number of colonies were carried away during the storm. Of 

 the remaining colonies, many were found in January 191 1 which had suffered 

 laceration to a considerable extent. The most common injury observed 

 was a destruction of the living tissues of the colony, such as would result 

 from twisting a specimen in one's hand while holding it firmly by each end. 

 The loss of branches in the branched forms, or the tearing of the skeleton 

 of the leaf-like portion of G. flahellum, was a very unusual occurrence. The 

 injuries caused by the twisting from the wave-action were quite evenly 

 distributed among the different species growing on this reef. Such injuries 

 often involve as much as half the total surface-area of each colony. In all 

 large colonies, of whatever species, the injury was greatest over the basal 

 portion, while the outer end or branches were usually uninjured. At the 

 time of the examination in January 191 1 there had been comparatively 

 little ingrowth of new tissue over the denuded areas, so that the extent of 

 the injury to any colony could be readily determined. 



When the same specimens were re-examined in July 191 1, in at least 

 50 per cent of the specimens noted as injured at the time of the earlier obser- 

 vations, the reparation had been so complete that there was no longer any 

 evidence of injury. In all of the colonies where the injury consisted in the 

 removal of living tissue from about the base of the skeleton, there was yet 

 an area where the skeleton was exposed. In all cases where the injury was 

 of this nature there was no evidence of any growth of the living tissue 

 down over the naked skeleton. The exposed skeleton was usually covered 

 with a dense growth of algae, bryozoa, or hydroids, so that there seemed to 

 be no probability that it would again be covered with the normal tissues. 



The examination of the same individuals in August 1912 showed com- 

 paratively little change since the previous summer. In some instances the 

 coenenchyma had grown down over the naked skeleton for some little dis- 

 tance, but usually the basal portions of the skeleton were, just as at the last 

 examination, covered with algae, incrusting bryozoa, etc. 



The leaving exposed of areas of the skeleton near the base of the colony 

 may have a causal relation to the fact that, on all of the shallow reefs, 

 gorgonians are found which are to a greater or less extent covered by an 

 overgrowth of Millepora alcicornis. In most cases the Millepora surrounds 

 what was really the basal portion only of a gorgonian skeleton. Not at 

 all uncommonly, however, a colony of Millepora is found which covers a 

 skeleton of Gorgonia flahellum, in which the mesh-work of the skeleton of 

 the "leaf" could be made out in all its details. Frequently the relation 

 between the height and width of the colony, as well as the characters of its 

 outline, showed that the Gorgonia had not suffered any disintegration before 

 being covered by the Millepora. As in a small number of instances the 

 Millepora was observed growing up about the naked skeleton at the base 

 of the Gorgonia colony, and as the complete naked skeleton of such a colony 

 is very rarely found in its natural attachment on the reef, it seems almost 



