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140 DENTAL IIISTOLOCY AND OPERATIVE DENTISTRY.

gingival line the fibers arc inclined slightly apically, passing over the
border of the jn'ocess to be attached to the outer layer of the ])eriosteuni.
These fibers are specially large and strong. Just at the rim of the
alveolus the fibers are inclined slightly apically and are inserted into
the bone, forming the edge of the process.
In transverse sections of the membrane in the gingival portion (Fig.
121) the fibers spring from the cementum in large bundles ; at the centre
of the labial surface they extend directly outward, breaking uj) into
smaller bundles, })assing around bloodvessels and bundles of fibers, and
blending with the fibrous tissue supporting the epithelium. Passing
niesially and distally toward the corners of the root, the fibers swing
around laterally and pass to the cementum of the next tooth. On the

Fi(i. 1-22.

Fibers at tlie border of the alveolar process (from sheep): D, dentin ; C, cementum; F, fibers ex-
tending from cementum to bone ; Bl, bloodvessel ; B, bone. (About 80 X.)

a]>proximal sides the fibers suddenly divide into smaller bundles, M'hich
wind in and out around bloodvessels, and bundles of fibers which pass
into the gingivus and are reunited into laroe l)undles to be inserted into
the cementum of the next tooth. On the lingual side the arrangement
is like that of the labial, except that the distance to wliich the fibers of
the membrane can be followed before they are lost in the fibrous mat of
the gum is usually greater than on the labial.
In the occlusal third of the alveolar portion of the membrane the
fibers pass, at right angles to the axis of the tooth, directly from the
cementum to the bone. In this position the fibers are large and do not
break u]i into smaller bundles, but the original fibers can be followed