some anatomists to be glandular organs,[1] which undoubtedly they are; but it is erroneous to assert that they "contain no trace of muscular fibres." Such fibres assuredly exist, and are most plentiful, lining the inner surface of the cavity, where they form numerous circular meshes of various sizes, bordering the orifices of the channels, that permeate the substance of the organ in all directions. Fibres, also, pass in every direction through the glandular mass of the walls. There can, therefore, be no question as to their being blood-propelling organs, though they are at the same time glandular.
Attached to these curious compound organs are the so-called "fleshy appendages" before alluded to, the true nature of which is still an enigma. They are usually of a rounded form, smooth externally, with the interior cavernous, wrinkled, and irregularly laminated. They are attached to the heart by a short, constricted peduncle and, on the opposite surface, there is an irregularly-formed opening, leading into the interior. The walls of the organ are composed almost entirely of a soft, tender parenchyma, formed, for the most part, of vascular ramifications, the trunks of which, three or four in number, communicate with the interior of the branchial heart, through the peduncle. The walls of these trunks and of the peduncle are composed of stout, tough membrane. The cavity of the appendage does not communicate with that of the heart, but opens, as we have seen, externally, or into the chamber within which the organ is placed, so that the fluid surrounding it will bathe its inner as well as its outer surface.
On examining microscopically, the membrane lining the inner surface, it is seen to be covered with minute, obtuse, cylindrical papillæ, filled with very small granular cells.
Difficult as it has been to determine the anatomy of this organ, it is still more so to assign to it its proper function, though it is evidently of much importance in the economy of these animals. We have seen, in the Loliginidæ, that these appendages lie within the great genital chamber, and are bathed by the fluid therein contained. And where, as in the Octopodidæ, this chamber is modified, there is a special apparatus provided, by means of which the appendages are still kept in contact with the fluid coming from that chamber. They therefore appear to have some relation to this fluid, the nature of which it becomes of importance to examine.
But first as to the genital chamber itself, and the others associated with it. In the Octopodidæ, as we have seen, there are five of these chambers, and only two in the Loliginidæ. These two, however, are homologically equivalent to the five in the former; which are made up by the renal chamber being divided by a septum, and by the two small additional, lateral chambers containing the cardiac appendages, the lateral chambers themselves being nothing more than
- ↑ Anatomy of the Invertebrata, by C. Th. v. Siebold, translated by W. J. Burnett, p. 292.
