52 ZOOPHYTES. 



B. Modes of Growth. 



58. There are several ways in which the mode of growth affects 

 the forms of zoophytes, depending on the two following considera- 

 tions : — 1. The mode of connexion between the bud and parent; 

 2. The mode of growth of the parent and its budding polyps. 



a. 59. The union between the bud and the parent may be simply 

 basal : the young starts out from the sides of the parent and forms 

 finally a prominent branch. Such is the case with the species here 



Fig. 24. 



Fig. 23. 



Anthophyllum cespitosum. 



Caryopliyllia arbuscula. 



figured. In figure 24, the branches thus formed are all distinct ; but 

 in figure 23, representing an Anthophyllum, the polyps are united 

 below in a common base, which gradually increases, as the whole 

 grows upward, and surrounds the lower part of the cells. 



60. In other instances, the bud and parent have a lateral connexion 

 nearly or quite to their summits, as is illustrated in the Astrajas, 

 Porites, and the massive corals generally. When this connexion 

 extends to the very summit, the polyps appear embedded throughout : 

 but otherwise they are more or less prominent above the general sur- 

 face ; and when the prominent part of a polyp secretes lime, the 

 corallum is covered with calides, as in the Madreporee, Dendro- 

 phyllife, Oculinse, Gemmiporse, and some Astrajee.* But if no cal- 

 careous secretions take place in this part, as in the Porites and 

 Gonioporce (§ 46), the cells are immersed, as in the case of immersed 

 polyps. The Gonioporse, and many Porites, when alive and expanded, 

 have the polyps standing prominent over the whole surface of the 



* See the figures 27, 28, 29, 31, and 34, as well as those of these genera in the Atlas. 



