414 STRUCTURE OF THE MUCOUS MEMBRANE. 
escaped observation, or have been confounded with irregular 
patches of aggregated glands. I have found them only in 
the lamellated mucous membrane, and principally on the 
valvulae conniventes. In this portion of the membrane they 
seem to take the place of simple follicles, which latter appear 
to be wholly absent. They occur in patches as large as a 
lentil, but perfectly flat, and are identical in structure with 
the mucous membrane of the large intestine, consisting of a 
reticular framework and alveoli. The septa somewhat thicker 
than those of the large intestine, measure (divested of epithe- 
lium) between F and of an inch in breadth, and contain 
from two to four rows of minute capillaries, which form a 
plexus with close meshes. The alveoli are polygonal, for the 
most part hexagonal in form, and somewhat larger than those 
Fig. 5. 
A portion of the free border of one of the valvulae conniventes of the 
jejunum, magnified nineteen times, and showing an alveolar and glandular 
structure, not hitherto described. The mode of transition of the lamel- 
lated into the alveolar structure is seen. The alveoli measured of an 
inch by 350, being as large as those of the stomach, and somewhat larger 
than those of the large intestine ; the septa measured between S g n and d<5 
of an inch in width ; the alveoli were shallow, and contained in their base 
a mucous gland with an excretory opening. 
of the large intestine, measuring (divested of epithelium) 
between and of an inch in longest diameter. Each 
contains a muciparous gland, which forms its floor, and the 
gland is furnished with a central excretory opening ; indeed, 
in every way, except in being somewhat coarser, this glandular 
structure is identical with that of the mucous membrane of 
the large intestine. Around the circumference of the glandular 
patch, the reticular structure is imperceptibly lost in the 
lamellae of the lamellated membrane. 
Peyers Glands . — The surface structure of the glandulae 
agminatae, Peyer’s glands, resembles that of the mucous 
membrane of the stomach, in being composed of a reticular 
framework with included alveoli; the floor of the alveoli 
being perforated by the apertures of numerous simple follicles. 
The raised portion of the network or septa measure (divested 
