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Show 604 MR. G. W. BUTLER ON THE [Dec. 3, The extent to which these fat-bodies project into the body-cavity varies, and that in a manner not merely dependent upon their size, hut also, so to speak, upon the ease with which the peritoneum separates from the body-wall. In such a Lizard as Tupinambis teguexin I have seen the fat-bodies projecting forwards into the peritoneal cavity as two yellow lobes, as large as the liver-lobes ; and this may be seen usually to a lesser degree in the common Green Lizard and in others. On the other hand, in a specimen of Gerrho-saurus flavigularis examined, these fat-bodies extend forwards into two spaces ventral to the peritoneum, without any free bulge into the body-cavity. A series of transverse sections taken through an Amphisbeena darwinii (cf. figs. 4-7), or a dissection of the animal, show that while anteriorly to the umbilical region the fat-bodies bulge into the body-cavity, in the more posterior region the peritoneum is simply displaced inwards. Thus we have here the two conditions above referred to displayed in different parts of the same animal; and this is true, in a less striking manner, of other Lizards (cf. figs. 11 & 12), in which the hinder portions of the fat-bodies are obviously quite outside the peritoneal cavity. The typical condition of these fat-bodies seems to be that of distinct lobed or festooned masses, suspended in distinct cavities l lined with smooth membrane, which are no part of the ordinary peritoneal cavity. It seems to me that to the extension of these cavities, which surround the fat-bodies, outside the peritoneum, so as to carry it away from the body-walls, we must attribute the peculiar state of things in Monitors, described by Beddard : (1) Proc. Zool. Soc. 1888, pp. 98-107 ; (2) Anatomischer Anzeiger, 1888, pp. 204-206. In the Monitors these two cavities communicate anteriorly, so as to form a single horseshoe-shaped cavity, with its free ends tbe alimentary canal into the substance of tbe fat-bodies, and regarding these and the liver simply as store-houses of combustible food-material, one is struck by the remarkable fore-and-aft symmetry displayed by the liver at one end of tbe trunk and the fat-bodies at the other, in their relations to tbe adjacent organs. And in this connection one is induced to comment upon the condition of the liver in Siphonopjs annulatus as described by Wiedersheim ' Die Anatomie der Gymnophionen,' p. 74, fig. 8 2 ) : - " Die Leber stelt e m langes, bandartiges in zahlreiches Lappen zerfallendes Organ dar. Die einzelnen Lappen entstehen durch tiefe circulare Einschnitte, liegen scbollenartig aufgereiht unt meistens in dichter gegenseitiger Beriihrung." The "Lappen" are in Epicrium "mehr gelblich gefiirbt," while in S. annulatus they possess "eine mehr graugriine Farbung." Again, it m a y be worth while to note here the fate of the liver in Petromyzon (cf. Schneider, ' Beitriige z. verg. Anat. und Entwick. d. Wirbel.,' Berlin, 1879, pp. 93, 91); Eolleston (' Forms of Animal Life') says, " A t the metamorphosis the tubular structure is lost; fat appears in the cells; the gall-bladder and bile-duct are absorbed." It must be remembered, however, that (as described in this paper) the fat-bodies in some Eeptiles project but slightly or not at all into the peritoneal cavity. 1 It m a y be sometimes, however, hard to trace distinct spaces round these bodies. |