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Diseases of the Horse's Foot by Harry Caulton Reeks
page 64 of 513 (12%)
A HUMAN FOETAL FINGER.[A] _a_, The nail; _b_, the rete mucosum; _c_, the
longitudinal ridges of the corium.]

[Footnote A: Seeing that the section is a longitudinal one, it would appear
from the way the ridges cut that they are running transversely beneath the
nail. Their extreme delicacy, however, prevents a single one showing itself
along the length of the section, and their constant accidental cutting
makes them _appear_ to run transversely (H.C.R.).]

THE HUMAN NAILS are thickenings of the lowermost layer of the horny portion
of the epidermis, the stratum lucidum. They are developed over a modified
portion of the corium known as the nail-bed. The horny substance of the
nail is composed of clear horny cells, and rests immediately upon a
Malpighian layer similar to that found in the epidermis generally. Instead
of the papillæ present elsewhere in the skin, the corium of the nail-bed is
marked by longitudinal ridges, a similar, though less distinct, arrangement
to that found in the laminæ of the horse's foot.

Having thus paved the way, we are now in a better position to discuss our
original question (Are the horny laminæ secreted by the sensitive?),
and better able to appreciate the work that has been done towards the
elucidation of the problem.

A most valuable contribution to this study is an article published in 1896
by Professor Mettam.[A] Here the question is dealt with in a manner that
must effectually silence all other views save such as are based upon
similar methods of investigation--namely, histological examination of
sections of equine hoofs in various stages of foetal development.

[Footnote A: The _Veterinarian_, vol. lxix., p.1.]
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