622 Original Articles. | Oct., 
fixed in the cement. At the base of the adult branches the cement 
is constantly deposited in much greater quantity than towards the 
extremities, and to this fact the increase in bulk is in great part due. 
It would appear, too, that the imbedded corpuscles are less numerous 
at the lower part than at the apex, or in the more recently-formed 
tissues. 
Tn the interests of general zoology, or the philosophy of the science, 
the determination of the origin of the axis is of material value, and to 
this point especial attention should be directed. In some families of 
the coralline group the polyp-stem is flexible, transparent, and recalls 
in some measure the horny or epidermic structures among the higher 
animals. Such are the Gorgonidz, whose zoological affinities bring 
them into close relation with coral; and hence, indeed, some authors 
have been led to believe that the axis of the latter, in spite of its 
solidity, was constructed by the induration of the epidermis just as we 
find the polyp-stem to be formed in the Gorgonide. It is, however, 
difficult, after the preceding investigations, to adopt this explanation, 
since in the interior of the coral axis we find elements similar to 
those which are disseminated through the deeper parts of the body of 
the polypes. In this matter a direct application of embryogenic re- 
searches has been made available for the purposes of classification. 
In conclusion, a few words may be devoted to the phenomena 
which precede the birth of the embryos, and which have not as yet 
received notice. Fertilization is accomplished under varying condi- 
tions, these having reference to the arrangement of the generative 
glands, and to the distribution of the individuals of different sexes 
upon the branches. The polypes, sometimes male, at others female, 
and lastly, again, hermaphrodite, may be found in close proximity with 
each other on a single branch, or separate and attached to different 
branches, where they are clustered together (and this is the most 
frequent condition), the number of one of the sexes is in excess of 
the other, very rarely a branch is unisexual, and I have never met with 
one exclusively composed of hermaphrodite forms. These latter, indeed, 
are relatively less numerous, and are most commonly scattered irregu- 
larly among others, or completely isolated in their very midst. The 
distribution of the sexes is not, therefore, subject to any special rule. 
Fertilization, it would seem, then, is sometimes direct, and carried on 
in a single polype ; at other times indirect, and effected between two 
individuals on the same, or on distinct branches, always, however, 
taking place in the general cavity of the body, since it is in this place 
that the ovum remains and is developed. Further, too, it would seem 
that the fecundating fluid must be carried to the female polypes by 
currents of water, as is the case with the mollusks which are of separate 
sexes, and furnished with adherent shells. The generative glands 
have no special well-marked form, as in most other animals; their 
products originating, so to speak, separately, at the base of the intes- 
tine-like folds of the general cavity, are contained in capsules which 
become prominent in proportion to their development, and which are 
ultimately attached to long pedicles. The ova, after the rupture of 
the pedicle by which they are suspended, fall into the general cavity and 
