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Show 176 MESSRS. SCHAFER AND WILLIAMS ON THE [Jan. 18, ration of pepsin, we hope that before long the results of some comparative experiments already commenced will enable us to form a definite opinion. In the foregoing account we have been induced to enter into what might seem almost unnecessarily minute details with reference to the structure of the gastric mucous membrane in these particular animals, because, as we have already incidentally mentioned, they seemed to us especially well adapted for investigation, partly on account of the well-marked differences between the glands of different regions, combined at the same time as they are with many unmistakable features of similarity, partly on account of the ease and certainty with which the regions can be mapped out, and partly also on account of the simplicity of form of the glands, which renders them easy of observation throughout their whole length. The identity between the glands of the third region here described and the well-known peptic glands of the stomach has been already incidentally noticed, and is sufficiently obvious. It will doubtless also have suggested itself to most of our readers that the glands here described as occupying the second region in the Kangaroo's stomach, and consequently by far the larger portion of the glandular mucous membrane, resemble in most points of structure those which were until the last few years known as the mucous glands of the stomach of Man and the higher Mammalia. But the resemblance is more obvious, both as regards situation and structure, in the part of the second region which is near the pylorus, than in the remainder. In the latter the epithelium of the glands presents peculiarities which have not hitherto, it is believed, been noticed in the gastric glands of other animals. These peculiarities are not improbably connected with the nature of the food on which the Kangaroo subsists. Further investigation is necessary to show to what extent they are found in other animals in which the food is similar. DESCRIPTION OF THE PLATES. P L A T E VIII. Fig. 1. Vertical section of the mucous membrane of the stomach of Macropus giganteus, carried across the line of junction between the first and second regions. Magnified about 135 diameters. A, end of first region or region of stratified epithelium ; B, commencement of second region; X , junction of the two ; 8, stratified epithelium ; p, p, papillae of corium rising up into this; c', lowermost columnar cells of the Mal-pighian layer of the stratified epithelium; h, horny layer of ditto; ty, lymphoid corpuscles between the cells of the Malpighian layer; gl, tubular glands of mucous membrane of second region; o, o, their orifices; c, columnar epithelium of the surface; i, i, interglandular tissue witb numerous lymphoid cells; m.m, muscularis mucosas; v, blood-vessels cut across. PLATE IX. Fig. 2. Vertical section of a part of the second region of the mucous membrane, showing three of the tubular glands, of Macropus giganteus. Magnified |
