Cuap. II, HISTOLOGY. 611 
The Ear. Soon after the ear has begun to develop, (Pl. 12, fig. 6,) the 
cells (Pl. 21, fig. 27) of the cup-shaped tympanic cavity are identical, in every 
respect, with those of the eye (fig. 28). 
The Intestine. A short time before the Turtle is hatched, the mucous layer 
of the cesophagus is composed of two layers of cells. The superficial ones (Pl. 21, 
fig. 1, fig. 5, a, fig. 6) are simply irregularly oval, or round, and have faint, 
granular contents. Their free surfaces are furnished with numerous vibratile cilia. 
By the application of water, the single mesoblast, and the single, double, or triple 
entoblast are brought out, (fig. 7, and 8,) and the mesoblast of the columnar cells 
may be recognized through the superior layer (fig. 8). The inferior layer (fig. 
5, 6) consists of long, cylindrical cells, (fig. 2, fig. 5, 6,) with scattered granular 
contents, and a single, homogeneous, hyaline mesoblast, situated near the broader 
end. Whilst in place, these cells are prismatic from mutual pressure, but being 
set free, they assume an irregular, club-shaped or spindle form (fig. 2). The super- 
ficial epithelial cells (fig. 14e) of the stomach, when seen endwise, appear sharply 
polygonal, of moderate size, and filled by densely packed granules, which almost 
obscure the large, single, oval mesoblast (fig. 14d). When seen in profile, they 
are deeper than broad (fig. 14c). By the action of water, these cells swell, and 
the granules are scattered (fig. 14f, 14g) so as to expose the dark, granulated 
mesoblast. By rolling these cells along the field of the microscope when they 
are very much swollen by water, it may very readily be seen that the mesoblast 
is attached to the wall of the cell (fig. 14g, a). By careful manipulation it was 
ascertained that the vibratile cilia on these cells are not scattered promiscuously 
all over the free surface, but form a crown to each one (fig. 8, and 4) along 
the line, where each cell touches its neighbor. The elongated cells of the thick 
intestine are arranged end to end, in three layers (fig. 34). They contain 
numerous, minute granules, and, when seen endwise, appear sharply polygonal 
(fig. 34a). If slightly acted upon by water, the large mesoblast is brought out 
quite clearly. 
The glands of the stomach appear as more or less elongated openings on 
the imner surface of the mucous membrane (fig. 14, a, I4a, 14b, 15, 15a), 
Around each opening a dark ring may be seen; every ring touching its neigh- 
bor: this is the outlme of the gland seen through the thickness of the epithe- 
lium. By plunging the microscope deeper, toward the outer surface of the stom- 
ach, the elongated, oval cells (fig. 15, 15a, 4, 16a) of the glands may be seen 
radiating from around the central cavity. Each gland is about four times as 
deep as broad, and consists of but one layer of cells (fig. 16b). These cells, 
in a view of the exterior surface of the gland, are irregularly polygonal; they 
contain a few scattered granules, and each a large, round, dark mesoblast in the 
