1907.] AND SUPPOSED SPECIES IN CORALS. 547 



repairing growth exhibits a strange independence, and, forsaking 

 the growth-form of the colony, builds its repair in the form best 

 suited to the new conditions of the environment. 



This is a strange zoological fact, that the inherent growth-form, 

 once stamped upon a well-established colony, continues to be the 

 type of growth, though it be but ill adapted to its habitat ; and 

 yet, when the continuity is once broken and a new start is made, 

 the newly-budded zooids can throw off the stereotyped method, 

 and build anew to the altered conditions. 



It is facts such as these that give some clue to the understanding 

 of the vast range of variation occurring within the limits of a 

 species, and make the establishing of a species a matter of extreme 

 doubt, until every possible variation tluit different surroundings 

 will stamp upon the type has been examined, We have seen, in 

 following the life-history of corals, that the colony shows great 

 adaptability, being able to mould its growth in i-esponse to the 

 demands of its environment, and in this repair process it possesses 

 a further power, for it can entirely alter the structure of an 

 established colony. 



Numerous examples of this strange pi-ocess may be seen. A 

 branching Montipore, growing in a gap in the island ring, is 

 found to have every colony dead or damaged in a greater or less 

 extent of its whole growth. The damage is probably due to the 

 fact that currents have altered the physical conditions of the 

 habitat since the founding of the colonies, and that a greater 

 rush of water has brought more sand and moving particles in 

 contact with them, for the apical branches of all the colonies 

 within a definite area will be found broken. The repair of this 

 damage invariably takes the form of an amorphous encrusting 

 growth covering the debris of the dying colony, the regenerated 

 portion keeping pace with the destruction, and thus keeping the 

 colony living — but living as an entirely different type of its 

 species. (PI. XXIX. fig. 1.) 



Madrepore colonies show the same phenomena, and very strange 

 repaii'-forms of Pocillopora growing in rough water as encrusting 

 growths may be found. 



When, after repair, a Madrepore colony assumes an encrusting 

 form, as it frequently does, the inherent tendency of its growth is 

 still evident, for rising at intervals from its flat surface are 

 numerous dominant zooids, which, were the opportunity afforded 

 them, would form upward-growing branches. 



It is by no means uncommon, in this process of repair, not only 

 for the vegetative growth of the colony to be altered, but for 

 the actual type of the corallum to be changed. When a Montipore 

 repairs its own ill-situated and dying colony by an encrusting 

 growth, the whole minute structure of the coral is changed. In- 

 stead of the smooth surface over which the fairly wide mouths of 

 the corallites are dotted, is a coral with an outward appearance 

 notable chiefly for its extreme roughness, due to the development 

 of numerous papillge at the bases of which open the minute 



