SCHIN. YOSCHIDA 
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penetrate Stratum Malpighii as they do in the Callosity and Ergot. 
The histological structure of the pad of the dog is in general similar to 
that of the cat. 
B. Histological Structure of the Ergot 
As I have related above, the Ergot, like the Callosity and the Pad, was 
originally a variety of the common skin, and its histological structure, there- 
fore, should resemble that of the other two ; when, however, it is studied in 
very minute detail some differences in the degree of divergence from the 
original are discerned. 
The result of my histological study is as follows, starting from the sur- 
face layer downwards : 
Stratum Mortificatum, in the Ergot, is very well developed and is very 
long. It consists of large and small scales, which, being delicate and flat, 
adhere closely together and are not easily rubbed off as in the pad of the dog 
and cat, and therefore grow long like a nail. As the surface of an unde- 
veloped Ergot is comparatively flat, the thickness of Stratum Mortificatum 
varies with the degree of development, but the other layers remain unchanged. 
Stratum Corneum, as in the Callosity and Pad consists of a layer of cells 
with hornified membrane, connected with a layer of Prickle Cells by Stratum 
Lucidum, In this layer Horntubes are to be found which are not seen in the 
Callosity and the Pad. These are formed by the tops of the elongated Papil- 
lae which penetrate Stratum Lucidum and the Prickle Cell layer. In a hori- 
zontal section Rohrwand cells and Horntube mark cells may distinctly be 
seen in these Horn tubes. 
Stratum Lucidum, in the case of the Ergot, shows no distinct connecting 
line with Stratum Granulosum, and the former is to be distinguished from 
the latter only because it is more difficult to stain. 
The Prickle Cell layer is very thick, with an average thickness of 1-3 
mm. It is penetrated by elongated and well developed Papillae and divided 
by them into interpapillary and su^JcM'papillary epidermis. On the base of 
