620 Original Articles. | Oct., 
the polypes. The one is due to the development of ova, the other is 
accomplished by the repeated appearance of buds. 
Before proceeding further, it will be necessary to give some general 
idea of the plan of organization. 'T'wo very different parts may be 
Ihiely 
A young polype, a, commencing to throw out buds, b; a colony, c, which has two polypes anda 
bud, d. At the tissues are laid open, so as to exhibit the first traces of the polypidom in process of 
formation. eisone of the spicules, magnified 900 times, which exist in the crust of coral, and which 
by agglomeration produce the poly pidom. 
recognized in living coral by the most superficial observation. The 
one—situated externally and, when recent, perfectly soft ; when dried up, 
friable and easily powdered—constitutes the polyp-bearing or animal 
layer (Fig. 3, a). The incorrect though convenient term which is 
frequently applied to this part of the animal is “bark.” The other, 
centrally placed, solid and resistant, forms the axis, polyp-stem, or 
trunk (Fig. 3, p). This part only is available for purposes of ornament. 
The surface of the cortical portion, when it is well preserved, and 
especially when quite recent, appears to be covered with minute bosses 
or little elevations. These bosses are pierced at their apex by a fine 
perforation with radiating folds, and are hollowed in their interior to 
form a cavity, from whence the polypes, or “nettles,” as Peyssonnel 
called them, appear to emerge. 
Nothing can compare with the graceful arrangement of these little 
animated flowers; the eight fringed arms with which they are pro- 
vided are in continual movement; extend themselves in every direction, 
and then again coil themselves up to convey to the central mouth the 
prey they have seized. They are milk-white in colour, and stand out 
in admirable contrast with the lively red of the base. Michelet, there- 
fore, is in error when, in his book on the Sea, he calls them flowers of 
blood-red tinge. 
The tissue of the cortical portion is cellular, soft, and delicate. 
It is furrowed throughout by vessels, either irregular in pattern 
(Fig. 3, ¢), or lying side by side and parallel (Fig. 3, d), and which put 
