ANATOMY OF THE ALIMENTARY CANAL. 
481 
The walls of the alveoli are composed of a framework of branching cells, 
united by a structureless membrane. 
Fig. 9. Camera Lucida: obj. 5, x300 — oc. hi., obj. 7. 
Villus of the small intestine of a rabbit : teased preparation. The intes- 
tine had lain four days previously in half per cent, bichromate of potash. 
The large cells composing the membrana propria are seen bordering the 
villus. 
v. Blood-vessel. 
Fig. 10. Camera Lucida: obj. 8, x600 — oc. in., obj. 11 immersion. 
Section of one of the villus-like processes of a rabbit’s colon. The epi- 
thelium is only drawn diagrammatically. 
v. Blood-vessel cut transversely. 
r. Dark line at the base of the epithelium formed by the reticulum 
surrounding the epithelial cells. 
vi. The muscle-fibres. They are seen apparently ending in the round 
or oval cells of the membrana propria. 
Fig. 11. Camera Lucida: obj. 7, x450 — oc. in., obj. 8. 
Section of one of the villus-like processes of a rabbit’s colon. 
m. A muscle-fibre. 
r. Reticulum. 
e. Endothelial cells of the membrana propria. 
Fig. 12. Camera Lucida : obj. 5, x 300 — oc. in., obj. 8. 
Cross section of the muscularis mucosae, from the rectum of a sheep. 
The reticulum is seen to surround the individual fibres, 
Fig. 13. Oc. in., obj. 8, x400. 
Section of a villus, from the small intestine of a monkey. 
m. A band of involuntary muscle-fibres. The connective-tissue reti- 
culum surrounding the individual fibres is attached to the 
membrana propria. 
Ap. Epithelium. The epithelial cells are seen to be of different 
lengths. 
r. Dark line at the base of the epithelial cells caused by the 
reticulum. 
Ic. Lymph-corpuscle. 
e. Endothelial cells of the membrana. 
v. Blood-vessels. 
The great similarity of the cells of the villus to the cells composing the 
membrana is seen. 
Fig. 14. Oc. in., obj. 9, x550. 
Section of the upper part of a villus, from the small intestine of a monkey. 
m. Muscle-fibres. 
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mdccclxxvi. 
