The Cutaneous Glands of (^ommon Toads. 329 



The epidermis is here very uniform and even, as compared to other 

 regions. (Figs. 2, 14, 23, 25, 57, 58.) The epidermis is usually 

 thickened and dips do^vn to form a pit about the mouths of the ducts 

 from the large glands. The thickening is due to an increase of 

 cells in the transitional stratum. The ducts of the small glands 

 do not, as a rule, cause a depression. 



The epidermis over the larger warts of the back and legs cor- 

 responds in the general structure to that over the parotids, except 

 that its thickness varies somewhat with the size of the wart (Fig. 

 21). The epidermis in the areas between the warts has a thickness 

 equal to only from one third to a half the thickness over the parotids. 

 Each stratum is here proportionately decreased through a change 

 in the size of the cells and in the number of layers. The transi- 

 tional stratum consists of two or three layers as compared to from 

 four to seven in the same stratum over the warts (Figs. 2, 3, 21). 

 The average thickness of the ventral epidermis is intermediate 

 between that over the warts and that of the areas between them on the 

 dorsal side of the animal (Figs. 4, 15). 



The Cutis. 



The cutis is far more varied than the epidermis. It is subject 

 to rearrangement occasioned by the increase or decrease of intrusive 

 elements such as the glands, nerves and bloodvessels. Its depth is 

 always greatest where the largest gland sacs are located (Figs. 14, 

 23, 24). It is least where they are entirely absent (Figs. 17, 18, 

 21-o.s.). In the latter areas of the back, the cutis is most typical 

 and uniform. 



Strata. The primary element of the cutis is the connective tissue 

 fiber. Apparent difference in the strata of the cutis is due to the 

 arrangement of the fibers for a specific purpose. I shall speak 

 of the outer loose, compact and inner loose strata, which are de- 

 scriptive terms (Figs. 17, 18). The compact stratum consists in 

 large part of bundles of fibers. These are closely associated and ex- 

 tend in different directions. In some areas the bundles occur in 

 successive horizontal sheets, approximately at right angles to each 

 other (Fig, 17). Other regions or individuals show these bundles 



