I/O 



PEABODY. 



[VOL. I. 



ered on either side with a single layer of cells. In the second 

 region, vis., that of the walls of the pockets themselves, two 

 layers of cells are always found. The peripheral layer, that is, 

 the thin sheet of cells next the lumen (Figs. 4, 5, p.c.}, has an 

 appearance almost exactly like that of the lining of the tube. 

 The cells are flattened, each being almost entirely filled by an 

 ellipsoid nucleus. Nucleoli are prominent. Beneath this thin 

 epithelial layer is a second layer composed of short cylindrical 

 cells (Figs. 4, 5, d.c.}. The nuclei, large and spherical in 

 shape, are situated at the very ends of the cells, next the 

 peripheral layer. The nuclei of the two layers can be easily 



distinguished, not only by 

 their difference in form, 

 but also by a difference 

 in their reaction to stains, 

 that is, those cells next 

 the lumen take a deeper 

 stain. 



Innervation of Ampulla. 

 -Five to ten nerve fibers 

 run to each ampulla (Fig. 

 i, a. n.}. I have never 



I 1 IG. 5. Region of Fig. 2 marked s.: c.c. *-3, centrum cell ; 



con.tis., connective tissue; d.c., deeper layer of cells; SCCn the fibers branch Or 

 P.C., peripheral layer of cells, x 465. . . . . 



unite with one another 



after leaving the nerve trunks. In branching, the nerve trunks 

 simply give off some of their component fibers. 



In studying the course of the nerves in the ampulla I have 

 employed the methylene blue method altogether, and this 

 method has given very satisfactory results. When the blue is 

 fixed in the ammonium molybdate with the addition of osmic 

 acid, a longitudinal section in a median plane shows that a 

 medullary sheath encloses the axis cylinder of the nerve along 

 its course up the centrum till just beneath the centrum cap, 

 where it disappears rather abruptly (Fig. 6, n.m.sh.}. In 

 freshly stained specimens, or where the stain is fixed without 

 the osmic adid, the blue-stained nuclei of Schwann's sheath are 

 distinctly visible. 



After the loss of the medullary sheath the axis cylinders pass 



