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Show 1876.] ANATOMY OF PLOTUS ANHINGA. 343 partment] about half an inch in diameter, which is lined with bristly hairs. They are all inserted at right angles to the surface, penetrate to the base of the epithelium, and are of various lengths, some of them not protruding beyond the surface, others upwards of half an • inch, of various colours, some black, generally tipped with whitish, others light greyish yellow, all thick at the base, and tapering to a fine point. Being disposed in a regular manner, they might seem to form a part of the organization of the stomach, and not to be, like the hairs found in Cuculus canorus and Coccyzus americanus, merely extraneous." The pyloric orifice in Plotus anhinga, as is seen in Plate XXVIII. fig. 2, is protected by a mat of lengthy hair-like processes, much like cocoa-nut fibre, which nearly half fills the second stomach. This second stomach is globose, and nearly an inch in external diameter. Its dense lining-membrane is raised into short rugae and tubercles, as is that of the first; and it is evidently a modification of the epithelium which develops these tubercles in the region of the pylorus which gives rise to the above-mentioned mat-sieve. The hairs composing the mat are hispid, slender, and about half an inch long. They arise from a surface a little less than a square inch in area round the pylorus, which is in its centre. They cease at the very margin of the small circular orifice, where the commencement of the delicate mucous membrane of the duodenum can be just seen. M y friend, Mr. E. A. Schafer, Assistant Professor of Physiology at University College, has very kindly examined these hairs microscopically, and tells me that " they are much more like true hairs, both in structure and mode of attachment, than they are like the epithelial projections which are so often met with over the filiform papillae of the human tongue, which, at first sight, they much resemble. Like hairs, they consist of an outer ' cuticular' part, and an inner ' fibrous' part; and in some places there is also yet another substance running along the middle of the fibrous part, which might be compared to the medulla of a hair. The cuticular part is much thicker in proportion than that of a cutaneous hair, and forms here and there dentate projections at the sides of the filament. The cuticle is continuous with the horny superficial portion of the stratified epithelium which covers this part of the stomach ; in neither can the outlines and nuclei of the component cells be distinctly seen, the cells having blended into a nearly homogeneous substance. That portion of the hair which extends below this into the deeper layers of the epithelium, appears not to be covered with a prolongation of the cuticle, but to be formed only of the fibrous part. This last-named seems, like the fibrous or cortical constituent of a cutaneous hair, to be composed of a closely set bundle of much elongated cor-nefied epithelial cells, slightly larger than those of a cutaneous hair, and with their extremities not fusiform (as in that) but truncated. The number in a cross section varies according to the size of the filament. They may, in many, be seen projecting at the end a little beyond the cuticular part. " The roots of the gastric hairs are so closely set as to occupy the greater portion of the mucous membrane, so that the connective |
