February, 1897. SOME NEW BOOKS. 1 25 



In selecting the habit of growth, that is, the mode of budding, as 

 the basis of his classification, Mr. Bernard has done the best that a 

 man can do who relies on external characters ; still, he seems but 

 little satisfied with his choice, and has a decided hankering after the 

 calicular diagnoses of Milne-Edwards and Haime. His method, 

 indeed, leaves something to be desired, as will be shown further on, 

 but it would not be improved by reversion to a method which 

 extended trial has shown to be unsatisfactory. It strikes one that he 

 is not consistent when he says (p. 20) " that the form of the corallum 

 is not altogether independent of the form of the individual calicle, the 

 corallum itself being but an aggregate of individual calicles." He has 

 shown just before that the characters of calicles may vary according 

 to their positions on the corallum, so that the corallum would appear 

 to determine the calicle rather than the calicle the corallum. The 

 growth of the corallum, again, is modified by local conditions, and the 

 growth of the corallum modifies the caHcles. In short, corals are 

 extremely sensitive to the influence of environment, and are highly 

 plastic. Hence tlie difficulties of classification. 



In order to account for certain structural features, Mr. Bernard 

 has called into being a new influence, that of the gravitation of the 

 nutrient fluid in the coenenchyme. He would have it that the nutrient 

 fluid runs downwards, is most abundantly supplied to the lowest 

 portions of the colony, and that excessive growth takes place there, 

 leading to immersion of the calicles. This is not quite a happy 

 conception : the region of most active growth is in the uppermost 

 portions of a normal crateriform colony, and where growth is greatest 

 the supply of nutriment must also be greatest. The gravitation theory 

 is quite inapplicable to numerous acrogenous forms of perforate corals, 

 e.g., Madrepova, and the phenomena which the theory is invented to 

 explain are better accounted for on other grounds, viz., that in the 

 older parts of the colony such growth as takes place is limited, both in 

 amount and direction ; it can only result in the fiUing up of the 

 cavities or in a thickening of the mass ; growth in the latter direction 

 leads to immersion of the calicles. 



It may be doubted, too, whether Mr. Bernard has formed 

 sufficiently accurate ideas as to the morphological value of the parts 

 of the corallum. Turbinarians, according to him, are purely 

 coenenchymatous corals, and he speaks of the skeleton of the polyp as 

 being built up entirely of the septa and their synapticulav connections. 

 Surely the use of the term " synapticular " is unwarrantable ; and the 

 references to coenenchyme and theca, or the absence of theca, betray 

 a want of precise conceptions respecting these structures. Those who 

 are acquainted with synapticulae as they occur in the Fungidae or in 

 Stephanophyllia formosissima will not hesitate to deny their homology 

 with the trabecular pieces which unite the septa in a perforate coral 

 such as Turbinavia. Compare again Von Koch's account of the 

 development of the skeleton of Astroides calymlaris, Dr. Fowler's 

 description of the anatomy of Rhodopsammia parallela, his description of 

 Turbinavia mesenterina, and a section made through any species of 

 Madrepova. In Astroides and Rhodopsammia one speaks of a theca 

 formed by union at many points of the peripheral ends of the septa ; 

 the theca is porous, permeated by canals, which communicate with 

 the ccelentera of the polyps. In Madrepova and Turbinaria the exsert 

 portions of the calicles have a structure to all intents and purposes 

 identical with that of Rhodopsammia and Astroides. The coenenchyme 

 is but an extension of the perforated theca ; it is permeated in the 

 same manner by a canal system ; and the characters of the corallum, 



