288 
STRUCTURE OF THE MUCOUS MEMBRANE. 
Fig. 1. 
A portion of the mucous membrane of the stomach magnified seventy- 
five times. The alveoli measured 335 of an inch in length, by 535 in breath ; 
the width of the septa being ttoo of an inch. The smaller aiveoli measured 
255 of an inch in length, and in breadth. The (itrifid or quadrifid division 
of a small artery is seen at the bottom of each alveolus, and in the depres- 
sions between the divisions of the artery, the apertures of the gastric 
follicles ; two, three, or four in each depression. 
in other words, the depth of the septa, is about of an 
inch ; and their breadth, that is the thickness of the septa, 
divested of epithelium, about yoVir of an inch. In struc- 
ture the reticulum is composed of a fold of the limitary mem- 
brane, containing the transparent granular substance of the 
surface of the corium and a plexus of capillary vessels. The 
capillary plexus of the reticulum is single, a disposition 
which probably determines the thickness of the septa; its 
meshes are large and open, and the vessels flexuous and ser- 
pentine in course. The border of the septum is formed by 
a capillary vessel, which sometimes runs in a straight direc- 
tion, and forms an even rim to the mouths of the alveoli, like 
that of a honey-comb; but more frequently makes abrupt 
curves and loops, which project before them the limitary 
membrane, and give rise to flat papillae. These flat papillae 
are chiefly found at the angles of the reticulum, and their 
existence in numbers gives a fringed appearance to the rims 
of the alveoli. 
The areolae of the reticulum or alveoli are polyhedral in 
figure, for the most part hexagonal, and slightly oblong ; about 
of an inch in depth at the sides, and somewhat deeper in 
the middle, and larger at the brim than at the fundus. Di- 
vested of epithelium, they measure in diameter at the brim 
between ^io and ttu °f an inch i n length, by and in 
breadth, and at the fundus something less. The floor is un- 
even, and presents in the centre the axis of a minute artery, 
from which two, three, or four, commonly three, capillary 
vessels pass off to make their way to the base of the reti- 
culum, and constitute its plexus. This little capillary axis 
naturally forms as many ridges in the floor of the alveolus, 
