680 ANATOMY OF THE MUZZLE OF ORMTlIOIiHryCIIUS, 



right up to the surface, but from the grailual way in which they 

 are, by this method, shown to taper off at their extremities, it is 

 probable that tiiey participate in the corneous change which 

 obtains in the epithelial cells of this region of the rod-organ, 

 and do not therefore react in the same manner to the reagents 

 as in the deeper region. The preparation was drawn with a 

 Zeiss' camera lucida. 



Fig, 2.— ( X 320 diameters). Vertical section of sweat-duct traversing 

 an epithelial cylinder (modified hair). The preparation from 

 which this figure was taken was cut from a portion of the 

 muzzle which showed remarkably little pigmentation. Accord- 

 ingly the outlines of the epithelial cells were not obliterated by 

 the perinuclear deposits of pigment and showed out with 

 distinctness. It was fixed in absolute alcohol and stained 

 with haematoxylin. 



a, epithelial plates forming the core of the cylinder; b, epithelial sheath 

 continuous with the superficial layers of the epidermis; h^, epitli. sheath 

 continuous with the malpighian layer of the epidermis; r, cuticle of duct 

 formed of fused epithelial cells; d, intra-epidermal portion of duct; r/i, infra- 

 epidermal portion of duct; r, medullated nerves ending by enlargements of 

 the axis-cylinder {k,) surrounded by a nucleated expansion of the primitive 

 sheath n; n', nuclei of nerve sheath; p, polyhedral epithelial cells in the 

 bulbous portion of the cylinder continuous with a above. 



Fig. 3. — ( X 320 diameters). Section of the deepest (secretory) portion of 

 the tube stained with haematoxylin. 



a, secretory epithelium cells; 6, small deeply stained cells wedged in 

 between the secretory cells. 



Fig. 4. — ( X 320 diameters). Transverse section of excretory duct stained 

 with haematoxylin. 



a, outer layer of columnar striated cells; /;, inner layer of flattened cells, 

 the outlines of which are not seen. 



Fig. 5. — (x 480 diameters). Transverse section through the bulbous portion 

 of the epidermal cylinder stained with haematoxylin. 



d, duct of sweat-gland; c, cuticular cells lining duct; p, polyhedral cells 

 of bulb; h, plate-like epithelial cells continuous with the superficial layers 

 of the epidermis (vide fig. 2); ^i, epithelial sheath continuous with the 

 malpighian layer of the epidermis (vide fig. 2); k, terminal enlargements of 



