530 A. B. DAWSON 
an accumulation of cells, often several layers thick, at the bottom 
of the duct, and marks the transition from the duct to the body 
of the gland. The bodies of the granular glands form large sacs 
extending, when seen in section perpendicular to the surface, 
completely across the spongy connective tissue, and the bottoms 
of many large glands depress the inner dermal layer. The 
gland sacs are usually somewhat ovoid, the perpendicular diame- 
ter (maximum 925 uw) being much greater than the transverse 
(maximum 700 yz). 
Where the glands are not crowded the typical ovoid outline 
is realized, and in horizontal section they then appear more or 
less nearly circular. If, however, they are closely packed and 
affected by mutual pressure, they appear in vertical section 
somewhat rectangular in outline, and in horizontal sections present 
a variety of polygonal shapes. The general form of both glands 
is the same except that the mucous glands usually present a 
slightly irregular outline, while those of the granular type always 
appear completely rounded. The mucous glands, moreover, are 
not so deeply inbedded in the dermis and, in regions where the 
granular glands are large and closely associated, those of the 
mucous type are found lying between the necks of the large 
glands immediately below the thin outer dermal layer. 
b. Histological structure. a) Ducts. The ducts of the granu- 
lar glands are usually cylindrical, but when the glands are highly 
developed the lower parts of the ducts are usually distended by 
the secretion which is forced upward from the sacs (fig. 6). When 
this occurs the epidermis is depressed and appears in surface 
view as a pit into which the duct opens. The epidermis sur- 
rounding the ducts does not exhibit any great differentiation 
such as has been described for many Amphibia. The cells 
immediately around the duct are, to be sure, modified in form, 
but no peculiar structures or staining reactions have been ob- 
served. In many other salamanders ‘funnel cells’ and ‘replacing 
cells’ have been described (Nicoglu, ’93; Ancel, ’02; Esterly, ’04), 
and Eberth (’69) speaks of a ‘stoma cell’ at the external opening 
of the duct in the frog skin. The cuticular margin, present on 
the outer layer of epidermal cells, is never found on the cells 
