Tho Cutaneous Glands of Oonnnoii Toads. 341 



that they are somewhat flattened (Fig. 69). In the proximal part 

 of the neck, the cells are polygonal in form. They are radially 

 placed in at least two irregular layers (Figs. YO, 71, 78). In the 

 collar the cells elongate, shift their position so as to appear as several 

 layers, but maintain their radial arrangement (Figs. 73, 74, 78). 



Cog-wheel-like structure. In the outlet just below where it passes 

 through the pigmented layer of the cutis, the cells form a cog-wheel- 

 like structure (Fig. 72.) The cells of the inner zone, thirty or more 

 in number, are radially arranged about the duct which at this point 

 is more or less circular. The cells of the outer zone are in groups 

 of ten or more, and the sixteen to twenty groups in turn radiate 

 from the inner zone. This structure is a constant feature of the out- 

 lets of the mature glands, and I have selected it to arbitrarily mark 

 the outer, limit of the gland collar. The distal ends of the first 

 sixteen to tw^enty muscle fibers extend to this point. The spaces 

 alternating with the groups of cells appear relatively clear when 

 stained, for at this level only the cytoplasm of the muscle fibers is 

 present ; the nuclei are at a lower level. Toward and passing into 

 the acinus wall, the fibers constantly increase in number, overlapping 

 in part those that have preceded them. At any given level in the 

 outer zone between the cog-wheel and the acinus, the muscle fibers 

 and the cells of the collar proper are intermingled with one another 

 (Figs. 73, 74). This arrangement provides a firm attachment for 

 the muscle fibers. Several authors (Schultz, Seeck, Phisalix) de- 

 scribe the collar of the species dealt with as consisting of elongated 

 cells, circularly arranged. Schultz even states that it approaches 

 the nature of a sphincter muscle. As we have seen above, all the cells 

 of the collar, have in the toad a radial arrangement. Esterly de- 

 scribes dilator and constrictor muscles in cells of the neck, which 

 lie against the duct. I have not been able to verify this in the 

 toad. 



Duct. The ducts of the mature glands vary both in their shape 

 and caliber. In the region of the epidermis, a duct has a slit-like 

 form, simple or branched (Figs. 69, 70). Often the epidermis is 

 depressed and appears in surface view as a pit or furrow at the 

 opening of the duct (Figs. 25, 67). But occasionally there is no 



