194 EDWARD B. POULTON. 
this layer is continuous with the outer and lower part of a large mass of 
epithelium bearing strong resemblance toa hair-bulb, but separated from the 
rest of the mass by a space (sp.) containing small branched cells. For the 
proper understanding of this part of the structure better material is much to 
be desired, for it is probable that considerable post-mortem changes had 
occurred. Within the supposed outer root-sheath the cylinder (the supposed 
hair) is surrounded by flattened cells (c.), which suggest the cuticle or possibly 
the inner root-sheath or both of these. This layer also arises from the sup- 
posed bulb. The central part of the cylinder consists below of polyhedral 
cells like those of the bulb, passing above into corneous fusiform scales with 
a longitudinal arrangement. The gland-duct (d.) passes into the lower end 
of the bulb, remaining distinct from the epithelium of the latter. In this 
lower part of the bulb the cells stain more deeply than those of the bulb, 
and their outlines are less distinct (compare Fig. 11). The duct is at first 
straight, but subsequently pursues a twisted course in the bulb, generally to 
a more marked extent than in the example figured. In the upper part of 
the bulb the duct becomes surrounded by a single layer of cubical cells, still 
staining rather more deeply than those external to them, but with distinct 
outlines. Above the point where the cylinder becomes corneous the duct 
appears to traverse its axis without any proper investment, the walls being 
extremely irregular and the lumen of a radiate star-like form in transverse 
section (compare Figs. 9 and 10). The whole arrangement suggests that the 
duct may have penetrated the bulb of a shortened and rudimentary hair by 
way of the papilla, and found its way along the medulla. Immediately below 
the bulb the duct is surrounded by a ganglion (gz.) containing large nerve- 
cells and medullated nerve-fibres, in which nodes of Ranvier are commonly 
noticed. Below this a large medullated nerve (z.) and the gland-duct (d’.) are 
seen in transverse section, while a curved gland-tube (g/d.) is shown to the 
left. The structure is evidently that of a Mammalian sweat-gland, a single 
layer of cubical gland-cells being surrounded by delicate fusiform smooth 
muscle-cells longitudinally arranged. 
The following four sections represent horizontal transverse sections at 
successively deeper levels of a gland-duct like that shown in Fig. 8, together 
with the associated structures. All probably come from a very similar locality 
on the upper bill. All are magnified rather over 400 diameters. 
Fic. 9.—Transverse section of the duct at about the level marked A in 
Fig. 8. Six papillary upgrowths mark the line of separation between the 
epithelium round the duct and the general epidermis of the bill. The corni- 
fication is more extensive than in Fig. 8. 
Fic. 10.—Transverse section of the duct at about the level marked B in 
Fig. 8. The lumen appears stellate in this and the previous figure. Of the 
six papille seen at a higher level, three have coalesced, while three remain 
distinct. Just below this level all six pass into the continuous dermal sheath 
