INTRODUCTION. 27 
were an independent organism as regards its growth, but its membranes are continuous 
with those of the parent. In many corals the base of the bud and the visceral cavity of 
the parent are at first continuous ; but in others the membrane reflected over the septa, 
the margin of the wall, the external surface of the wall or of the base, produces the 
gemimation. 
The gemmation may take place, then, on any part of a coral. It may occur within 
the calice, on the calicular margin, on any part of the wall between the calice and the 
base, and it may happen at the base. The direction of the line of growth of the bud has 
much to do with the future shape of the corallum, and the power of growth of the parent 
corallite after the development of the bud also. 
The parent corallite may not grow after the production of a bud from its external wall ; 
the bud becomes a perfect corallite, and gives origin to a bud inits turn. This repetition 
may go on, and a corallum results, formed by an ascending series of simple corallites ; or 
the parent corallite may elongate after giving off a succession of whorls of buds which do 
not in their turn always develop others. The space between the whorls and the individual 
buds becomes filled up with exotheca and coenenchyma, A dendroid corallum results, as 
in the genera Madrepora’ and Stylophora. 
Again, straight cylindrical corallites give off one or two buds, and all continue to grow, 
passing upwards, the calices keeping on one level, and the corallites being parallel. This 
determines the massive corals of many As/reide. 
A corallum with geometrical calices whose walls are soldered together buds within 
the calices ;? the parent calice and the bud grow, and the coral both expands laterally and 
increases in height. ‘This produces a very common form of compound coral. 
Certain corals never raise themselves far from the foreign substance they rest upon ; 
the base gives off a bud, which, stolon-like, gives forth others, and all turn upwards 
slightly. 
From these considerations it is evident that there is a necessary division of the 
gemmation into calicular, basilar, and lateral. 
Calicular gemmation takes place from the interseptal loculi near the columellary space, 
and either midway between it and the wall, or just within the calicular margin. One or 
more buds may grow at once, and the budding may or may not be fatal to the parent. A 
pseudo-calicular gemmation is occasionally seen in simple corals which are only oviparous. 
It is produced by one of the young polypes settling on the parent accidentally, and 
growing to its detriment.° 
The true calicular gemmation is well seen in the simple forms of the genus Cyatho- 
Phyllum,* 1 a new genus from the Lias (Lepidophyllum), and in the genera Stauria,? 
Isastrea,® &e. 
1 Pilate IV, fig. 18. 2 Plate IV, fig. 11. 3 Plate IV, figs. 8, 10. 
4 Plate IV, fig. 10. 5 Plate III, fig. 15. 6 Plate IV, fig. 11. 
