ANATOMY AND PHYSIOLOGY OF THE HORSe’s FOOT. 705 
of touch ; while others, again, have imagined that they serve 
merely as moulds for the horny material constituting the 
wall, sole, periople, and frog. Observation and experiment 
have apparently furnished proofs in favour of each particular 
view, and the question would even now appear to be a vexed 
one as to which is the correct statement, or whether they are 
not all more or less to be substantiated by a renewed and 
impartial examination. 
We will not at present enter into the supposed tactile 
function of the villi, but inquire what share they take in the 
secretion and peculiar arrangement of the horn composing 
the hoof. In investigating the histological structure of this 
part, it was remarked that the cells of wdiich it is constituted 
were arranged in two orders : a vertical, forming the walls of 
each tube or fibre, and a horizontal, occupying the space 
between the fibres. Each fibre or tube, for a certain portion 
of its length, was also observed to be occupied by a villus, 
whose structure was stated to consist of a beautifully fine 
tuft of blood-vessels enclosed in a delicate membrane — the 
common envelope of the keratogenous surface — and which, 
when withdrawn from the horny case, was usually covered 
with layers of epidermic cells either fully formed, or in process 
of development ; while the lower part of the tube was filled 
by an accumulation of epidermic cells arranged in no definite 
manner, but rather packed irregularly together by the simple 
force of concussion. 
This disposition of the cells, together with the structure of 
the villus, might be considered to afford sufficient evidence 
as to the manner in which the fibrous portion of the hoof is 
formed, and the role assigned to the villi in its production. 
The villi and the intervillous space being alike covered by 
the horn-producing membrane, it is hut reasonable to suppose 
that both possess and exercise the same keratogenetic faculty ; 
and that they do so is amply demonstrated by clinical or 
experimental observation. This leads us to consider the villi 
as chiefly concerned in the production of the fibres, while the 
space between them secretes the horizontal cells that unite 
these fibres, and bind them into a solid mass. 
Whether each villus has the same formative power through- 
out its entire length is another question ; but there can be no 
doubt whatever that the cavity of the tube it forms is wider, 
and has thinner walls at its commencement than at a short 
distance below, and that the increased thickness and 
diminished capacity is due to the continual addition made to. 
its interior by the generating surface of its contained villus. 
The presence of newly formed cells for a certain extent in the 
