OCR Text |
Show 1883.] TONGUES O F T H E MARSUPIALS. 627 processes are still fused into a single upgrowth, crescentic in section (p.p.p.). At a higher level than is shown in this section the complete ring of secondary processes would be distinct. Hence the posterior papillary processes are given off at a higher level (compare fig. xxvi.). S. h.p. Single hair-like papilla?, as in fig. XXIII. This section shows that the upgrowths for the isolated hair-like papilla? are very distinct from those of the coronate papillae even at the lowest levels. Fig xxvi. X 145. A single coronate papilla from the region between the two anterior circumvallate papillae of Macropus melanops, shown in perspective from the left side. The secondary papilla? are probably finer than in reality. Fig. xxvir. x 10. Vertical longitudinal section along the middle line of the papillate surface in front of the anterior circumvallate papilla? of Halmaturus ualabatus. The section shows the relation of the isolated fine papilla3 (s. h. p.) to the coronate papillae (c.p.). Fig. xxviii. X 40. Horizontal section through the coronate papillae of Halmaturus ualabatus, taken in the middle line just anterior to the posterior circumvallate papilla. This also shows the relation of the isolated (s. h. p.) to the coronate papillae (c. p.), and also indicates that the secondary papilla? on the latter are not always regularly arranged in the ring. The posterior side of a coronate papilla can sometimes be detected by the fact that some of the posterior secondary processes remain still coalesced, although they are distinct at other points of the circumference, i. h. p. Single hair-like papillae within the ring of some of the coronate papilla?. Fig. xxix. x 40. Vertical longitudinal section through a coronate papilla (vertical transverse through the organ), just above the lateral organ of Halmaturus ualabatus. The figure shows the relations of the four layers of a complex epithelium to the papillary structure. The layers are : - 1 , staining moderately, the cells fusiform and nucleated ; 2, a thin layer, behaving with reagents as if the cells were cornified; 3, deeply staining, elongated cells with long thin nuclei; 4, a layer presenting all the characters of normal rete Malpighii. The distribution of layer (2) in the secondary papilla? (p. h. p. and a. h. p.) also indicates that it is cornified. The same layers are met with in the smooth epithelium beneath the papillate surface (see fig. xxxi.). The shading is diagrammatic. In other parts of the organ, the distribution of layer (2) is more symmetrical in the secondary papillae. Fig. xxx. x 50. Vertical longitudinal section thiough a coronate papilla from the surface above the tip of the tongue of Phalangista vulpina. The figure shows the arrangement of the cells much resembling that described in Perameles, but more complex. The normal lower layer (n. I.) graduates into attenuated granular cells (a. c), passing through a mass of similar cells of which the nuclei stain deeply (n. c), into the very attenuated cells of the posterior process (p. c), in which hardly any nucleus can be detected. Above, in the centre of the main papilla, the cells are still granular, but swollen and non-staining (s. c), while remnants of the nucleus can be often detected. Higher still, and towards the posterior secondary papilla, the cells again become attenuated, rarely nucleated, and deeply staining (a', c'.), and they are continued on to the posterior papillae. The swollen cells pass directly into the attenuated cells of the anterior papilla without forming a layer in the main coronate papilla. All the secondary papillae also derive cells from their own papillary upgrowths, and also from the superficial epithelium surrounding them. The latter is simple and of the usual structure. Fig. xxxi. X 14*5. Vertical transverse section through one of the elongated depressions of the lateral organ of Halmaturus ualabatus. The depression (a. d.) is seen to present all the characters of a gland-duct, and a secondary duct opens into it above the region of the taste-bulbs (t. b.). In the epithelium the four layers described in fig. xxix. are shown. |