154 
Harley^ on Cutaneous Respiration. 
very often present a ragged appearance. If, on the other 
hand^ these bodies are made up of minute fibrillsS;, surrounded 
by a membrane_, to which they are attached^ the fibrils are so 
intimately connected with each other^ that they cannot be 
separated except by tearing. 
The integument of the frog^ besides containing a great 
number of blood-vessels^ is freely supplied with nerves. These 
have been very ably described by Czermak^ and for the 
most part my observations confirm his. In one pointy how- 
ever^ we diflPer ; he says that many of the subdivisions of the 
nerves pass from the under to the upper surface of the skin 
through the perpendicular fibres, which, as was before men- 
tioned, he regards as canals. The special purpose of these 
tubes or canals being to form a protecting sheath for the 
nerves, which, on reaching the upper part of the cutis vera, 
are reduced to merely the axis cylinder. As I regard these 
canals as a peculiar form of smooth muscular fibre, I cannot 
suppose that the nerves penetrate into, but only pass along 
the side of them. 
There is yet a structure in the superficial layer of the cutis 
vera of the frog, which, as far as I am aware, has been de- 
scribed by no previous observer. It consists of a number of 
oval bodies, not at all unlike very small Pacinian corpuscles. 
These bodies are exceedingly numerous, and are distributed 
among the pigment- cells of the rete mucosum. I frequently 
attempted to trace the axis-cylinders of the nerves into these 
peculiar bodies, but without success. They are best seen when 
a weak solution of caiistic potash is added to the skin, freed of 
its epidermis, in order to make it more transparent, and are 
roughly represented at PI. VI, fig. 5, b. 
The frog is not the only animal which has cavities in the 
skin, the mouths of which are covered over with a layer of 
tesselated epithelium. I found a similar kind of arrangement 
to exist in the skins of the newt and common water-lizard. 
In these animals, however, the cavities are of a somewhat 
different form, and less numerous than in the frog. The 
aperture in the middle of the tesselated epithelial covering 
of the lizard^ s skin is not of a triangular, but of an oblong 
shape ; it sometimes measures as much as mm., and con- 
sequently may be said to have a still closer similarity to the 
ordinary form of vegetable stomates. The following descrip- 
tion of the stomates of plants is given by Professor Lindley, 
in his ' Elements of Botany " Stomates are oval spaces 
~ lying between the sides of the cells, invariably opening into 
intercellular cavities in the subjacent tissue. This descrip- 
tion of the stomates of plants cannot fail to strike the reader 
