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Show 130 MR. W. E. HOYLE ON THE [Mar. 5, Towards the margins of the pads the peculiarities of the epithelium gradually disappear. The cells become shorter, their nuclei more deeply stained, and they pass by insensible degrees into the flattened pavement epithelium winch lines the rest of the siphon. At the anterior extremity of the organ it is raised up into a free process, which is completely surrounded by the layer of these highly refractive bodies. I have also examined sections of this organ in the case of Taonius both young and adult, in the embryos of Ommastrephes, Sepia, and Loligo. In its general features the minute structure of the organ is the same in all these instances, but it was only in Gonatus that I was able to discover the highly refracting globules described above. What the relation of these may be to the fusiform rods described by Muller and Boll I will not attempt to decide at present, but must leave any further histological discussion till an opportunity offers for describing its structure in Taonius and other forms where it is highly evolved. I shall, however, venture a suggestion as to the fuuction which it possibly discharges, because a hypothesis, even though it may eventually prove to be mistaken, affords a useful guide in subsequent researches. The theories of a sensory or of a phosphorescent purpose in this organ seem to be sufficiently negatived by its situation in a closed space through which only effete products from the body are discharged. Brock is, 1 think, in error when he states that the main interest of this organ is that it affords an instance of the occurrence in Mollusca of nettle-cells or of bodies allied to them. To my mind the resemblance to nettle-cells is purely superficial. Muller, who noted it, distinctly remarks that they have no filament, and Boll, as above mentioned, did not think that they were so much like nettle-cells as like the rod-bearing cells of the Turbellaria-an opinion which is fully borne out by his figures. The view that the modified epithelium discharges some secretion seems on the whole the most feasible, and is supported by the existence of the structureless layer observed on the surface of the epithelium, which, it may be remarked, is of considerable thickness in the adult Taonius. The difficulty hitherto has been to discover the purpose served by this secreted matter. I would suggest that possibly this funnel-organ is an apparatus for the closure of the funnel, that it is, in fact, functionally, though not morphologically, a valve. I am led to this conclusion by the following considerations:- 1. The fact that in a very large number of sections which I have examined the pads are so disposed as to very nearly, if not quite, occlude the lumen. I need only refer to the two instances figured in the woodcut as examples. 2. The fact that in those forms in which the organ is most highly differentiated in the adult the valve is absent, as for example in the genus Taonius. 3. In this case the presence of a sticky or viscous secretion would be of obvious utility in securing the more perfect apposition of the |