CONCLUDING NOTES. 423 



the subject in a paper entitled, " Some Notes on Variation and Protandry in Flabellum rubrum 

 and Senescence in the same and other Corals'," but I draw further attention to it here, in 

 the hope that future visitors to coral-reef regions will pay attention to the subject. "If — 

 as I am impelled to believe — the ripening of the generative organs of a large number of 

 polyp colonies of the same species in a single locality or habitat, followed by the subsequent 

 death of all these colonies, is a regular phenomenon, the consequences must be of the most 

 wide-reaching importance in the formation of coral reefs." " Remembering the occurrence of 

 a ciliated larva in the Madreporaria, it is impossible to believe that the colonies of a single 

 species in any area are of the same age — they certainly are not of the same size, and hence 

 have not a like number of polyps. It is consequently necessary to suppose that in an area — ■ 

 owing probably to some change in the physical conditions of their environment — all the corals 

 of some single species have been stimulated to ripen and dehisce their generative products at 

 the same time, the act leading ultimately to their weakening and death." The only analogous 

 case that I know of in nature is that of the bamboo, every plant of which in a district 

 produces its fructification at the same time and dies'-. The analogy is not complete, how- 

 ever, for whereas the individual polyps of a colony go on pi'oducing ova or spermatozoa during 

 the whole of their life, the bamboo merely sets one enormous fructification, which apparently 

 uses up all its energy and causes its death. 



At the last meeting of the British Association, and in the last Part of this Publication', 

 I discussed to some extent the importance of algae as agents in the disintegration of corals. 

 As I go to press I have to thank Mr J. E. Duerden for an important paper on this subject, 

 which he has been kind enough to send me. Mr Duerden's conclusions, derived mainly from 

 the examination of W. Indian corals, are strikingly in accordance with mine, and go much 

 further with regard to this one class of organisms. Mr Duerden-* found in 30 W. Indian 

 corals that he examined the tubes of algae of the genera Gomontia and Ostreobium penetrating 

 every part of the different coralla, but their living filaments were only present in the more 

 superficial parts of the different colonies, to which alone light could penetrate. Twelve frag- 

 ments of coral, obtained by Prof Agassiz in the Pacific in 1899 — 1900, when decalcified revealed 

 in every case the presence of filamentous algae. " The results presented above give good reason 

 for assuming that in general all corals are infected with boring algae, even to their most super- 

 ficial regions of growth." " Once a coral is attacked by these (algae), the growth of the 

 ramifying filaments apparently never ceases so long as the necessary conditions of plant life 

 remain; even when the dead coral is broken up into fragments the growing filaments still 

 continue their corroding action on the separate particles, and by the production of soluble 

 bicarbonates lead to their ultimate disappearance." 



[Note. For an account of the biology and species of the reef-building plants see " The 

 Lithothamnia of the Maldives and Laccadives," by M. Foslie in the same Part of this 

 Publication.] 



' Proc. Camb. Phil. Soc. vol. xi; pp. 463 — 71 (1902). tionally inferred that the phenomenon was found only in 



^ Mr W. T. Blanford in a letter remarks that he has cultivated ones. 



" seen more than one instance of a particular species of ' Vide p. 32-5, and also p. 116 in Part 2. 



bamboo having perished over hundreds of square miles of ^ " Boring Algae as Agents in the Disintegration of 



country." He further points out that the bamboos are wild Corals," Bull. Amer. Mus. Nat. Hist. vol. xvi. pp. 323 — 332 



plants, whereas in the paper already referred to I uninteu- (Sept. 25, 1902). 



