Nerves to the Skin of the Frog, 
19 
their respective fibres^ and as they arrive at the capillary net- 
work/" there they form an intricate plexns with rather narrow 
meshes. The plexus_, which, for the greater part, lies imme- 
diately beneath the capillaries (only a few bundles of the finest 
kind passing over them), is not composed of single separate 
fibres, but of bundles alternately exchanging their fibres. 
The fine bundles composing the plexus above referred to 
are connected, at unequal intervals, with certain small bodies, 
or nuclei, as they are usually termed, which vary both in size 
and shape. They are either oval, or triangularly, or indeter- 
minately shaped. Carmine solution colours them deeply, and 
under the action of diluted acetic acid they appear uniformly 
granular. If oval, they usually are found imbedded among the 
nerve-bundles, but if they present a triangular or some other 
shape, their ordinary seat is either at the point at which a 
bundle divides, or where two or more bundles meet together. 
These small bodies are in general far less numerous than the 
oval nuclei, which are found in connection with the dark- 
bordered fibres, and by the size and the relation they bear to 
the pale fibres greatly differ from the nuclei connected with 
the dark-bordered fibres. In fact, as already stated, the 
nuclei of the dark-bordered fibres are commonly equal in 
width to the fibre, and their long axes are parallel to the latter. 
They are separated by short intervals, and seem to be situated 
within the white substance, and sometimes to be actually con- 
nected with the axis cylinder itself. On the contrary, the small 
bodies which are found in connection with the terminal pale 
fibres are generally much broader than the fibres connected 
with them, and their relation to the latter is, in a certain 
respect, similar to that which the nerve-cells bear to the 
fibres arising from them. It appears to me, therefore, quite 
unreasonable to comprehend under the same name things so 
widely diflFerent. 
Respecting the intimate structure of the pale fibres in con- 
tinuation with the dark-bordered fibres, my own observations 
lead me not to consider them as a mere prolongation of the axis 
cylinder. I agree with Kolliker on this point, and firmly believe 
that the pale fibres derived from the dark -bordered fibres, be- 
sides the axis cylinder, are provided with the tubular membrane^ 
and a very thin layer of white substance^ which can only be 
* In order to avoid misapprehension, it must be borne in mind tliat, in 
the derma of the frog, the capillary vessels are so arranged as to form two 
networks ; the one, with wide meshes, is seated in the inner, the other, with 
narrow meshes, is seated in the outer layer. These two networks are con- 
nected with one another by a few intermediate capillaries, which simply 
traverse the middle layer of the derma in nearly straight directions. 
