the
cuticle, of which they constitute a part.

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How can it be spread along the hairs? Why should soap not be used in
washing the hair? 721. Of what use is the hair upon the head? About
the flexions of the joints? In the nasal and ear passages? Upon the
eyebrows and eyelids? 722. Describe the nails. 723. How are they
formed?

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_Observations._ 1st. The nail upon its under surface is fashioned into
thin vertical plates, which are received between the folds of the
sensitive skin. In this manner, the two kinds of laminae reciprocally
embrace each other, and the firmness of connection of the nail is
maintained. If we look on the surface of the nail, we see an
indication of this structure in the alternate red and white lines
which are there observed. The former of these correspond with the
sensitive laminae; the latter with the horny plates. The ribbed
appearance of the nail is due to the same circumstance. These
sensitive laminae are provided with an unusual number of capillary
vessels for the formation of the nail, and hence they give a red tint
to the portion under which they lie.

2d. Near the root of the nail there is a part that is not laminated,
and it is less abundantly supplied with blood-vessels. This portion
consequently looks pale compared with the laminated portion, and from
its half-moon shape is technically termed _lunula_. Beyond the lunula,
the root of the nail is imbedded in the fold of the sensitive skin,
and has the same relation to that structure that any single one of the
thin horny plates of its under surface has to its corresponding pair
of sensitive laminae.

724. The nails, from their position, are continually receiving
knocks, which produce a momentary disturbance of their cell
formation, followed by a white spot. The care of the nails should
be strictly limited to the knife or scissors, to their free border,
and an ivory presser, to prevent adhesion of the free margin of the
scarf-skin to the surface of the nail. This edge of the cuticle
should never be pared, the surface of the nail never scraped, nor the
nails cleaned with any instrument whatever, except the nail-brush,
aided by water and soap. An observance of these suggestions, will
prevent irregularities and disorders of the nails.

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Give observation 1st. Observation 2d. 724. How should the nails be
treated to prevent irregularities and disease?

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