548 DR. F. w. JONES ON GROWTH-FORMS [June 18, 



covaliites (PI. XXIX. fig. 1). The characters of the original 

 growth and of the repair growth are so entirely different, that 

 they would certainly be regarded as two distinct species. Other 

 examples of this entire change are not uncommon, and some very 

 strange abnormalities may be found, which show that in repair, 

 as in adversity and in alteration of environment, there is practically 

 no limit to the developing of the diflerent main types of growth 

 by any coral. It is common in repair of injury as it is in cases 

 of adversity, that the bounding walls of the newly-budded zooids 

 are never completed, and repair by a pseudo-meandrine form of 

 fission is often met with in many and widely-separated species of 

 coral (PI. XXIX. fig. 2). It is common, too, to find that the 

 repair-zooids have raised coralla, wdien those of the parent colony 

 are flat, and in these cases it is probably silt that has caused the 

 original damage. 



The study of the repair in corals is therefore one not devoid of 

 zoological interest, for it shows clearly tha.t a type must never be 

 considered as a species, in the way in which we regard species 

 among the higher animals, until it has been seen in all its 

 variations, and until all the possible modifications that repair 

 produces have been studied. 



That a type like the encrusting Montij^ore should be in 

 I'eality the same species as the bi*anching form, would be con- 

 sidered as highly improbable, but when it is seen that the one 

 type repairs its damage by the development of a new growth of 

 the other type, there is no alternative but to regard them as 

 identical species. 



That the numerous types of Millepora and of Pocillopora should 

 be but variants of a single species would seem at first sight to be 

 ^'er3^ unlikely, for there is little enough likeness between the 

 extreme forms, and yet their processes of repair show them capable 

 of building to any of their diverse types, regardless of the nature 

 of the parent growth. 



If the processes that have been described, and the conclusions 

 that have been drawn from them, be accejJted. they can serve only 

 to make clearer the great fact that morphology — the animal's 

 type — is the outcome of necessity ; and here the demands of 

 necessity bring about change, not in the life-history of a species 

 only, but in the life of the individual. 



Since these repair-forms are the outcome of the partial death 

 of the colony, and since the growth-forms of many colonies are 

 detennined by the normal, or abnormal, death of portions of their 

 surface, it will be well to briefly review the processes by which 

 death overtakes a colony. 



The subject of repair leads naturally to the consideration of the 

 death of the organism, foi- when the destructive processes outweigh 

 the resources of repair, then death must inevitably ensue. 



There is one fact in the life-history of corals that the study of 

 their processes of repair clearly brings out, and it is this, that all 



