chamber, and that consequently we have here a rudimentary form of the lymphatic system.
This suggestion is to some extent corroborated by the nature of the branchial hearts, into the midst of the glandular walls of which the lymph is apparently thrown, and there probably undergoes some assimilating influence, on its passage into the circulation, like that which is supposed to be exercised by the spleen, and the other glandular appendages in connexion with the lymphatic system of the higher animals.
It would thus appear that these so-called water chambers form a diffused kidney, having, probably in connexion with it, a rudimentary lymphatic system. It is, however, generally believed that they receive water into their cavities from the exterior; but it is not easy to conceive for what purpose the raw element should be thus admitted to bathe the surfaces of the various delicate organs that lie within these cavities. There is nothing to give colour to such an opinion, except the fact that the renal chamber opens externally; and yet it would have been rather extraordinary if no such orifice had existed to admit of the escape of the urine. And, moreover, it is evident that this opening, which is, so far as my experience extends, always more or less nipple-formed, is ill calculated for the ingress of fluid, while, on the contrary, it is perfectly adapted for its egress. The same is the case with regard to the passages of communication between the renal chamber and the other portions of this so-called water system. This is most strikingly so in the Loliginidæ, in which it would seem impossible for the fluid in the renal, to pass in a backward direction into the genital chamber; though the passages are most admirably formed to allow the flow of the fluid in the opposite direction,—the tubes connecting the two chambers opening into the renal chamber, much in the same manner as the ureters do into the bladder of the higher animals.
Neither have I yet been able to satisfy myself of the existence of any water canals, or system of water chambers, opening externally in the neighbourhood of the head or tentacles. Some writers appear to have taken the olfactory openings for orifices leading into such aquiferous passages or chambers, and probably some of the other openings described, are nothing more than mucous pores. But this branch of the subject requires further investigation.
Before concluding, one or two points of detail may be mentioned in connexion with the vascular system. With regard to the heart, I can find nothing deserving the name of pericardium. The renal chamber has been so designated; but, as we have seen that the heart is never placed within it, this is evidently a misnomer. The heart, in some of the Loliginidæ, lies within the genital chamber, but is not enclosed in a special receptacle. The membrane, forming the wall of the chamber, is apparently reflected over it, though it is so completely incorporated with the surface of the organ as not to be demonstrable. In the Octopodidæ the heart lies in the cellular tissue, between the renal and genital chambers, and is more or less enveloped by the
