rom half a minute to two minutes.

Horrocks ascribes to these anal tags a pathologic importance. He claims
that they may be productive of fistula in ano, superficial ulcerations,
fecal concretions, fissure in ano, and that they may hypertrophy and
set up tenesmus and other troubles. The presence of human tails has
given rise to discussion between friends and opponents of the Darwinian
theory. By some it is considered a reversion to the lower species,
while others deny this and claim it to be simply a pathologic appendix.

Anomalies of the Spinal Canal and Contents.--When there is a default in
the spinal column, the vice of conformation is called spina bifida.
This is of two classes: first, a simple opening in the vertebral canal,
and, second, a large cleft sufficient to allow the egress of spinal
membranes and substance. Figure 130 represents a large congenital
sacral tumor.

Achard speaks of partial duplication of the central canal of the spinal
cord. De Cecco reports a singular case of duplication of the lumbar
segment of the spinal cord. Wagner speaks of duplication of a portion
of the spinal cord.

Foot records a case of amyelia, or absence of the spinal cord, in a
fetus with hernia cerebri and complete fissure of the spinal column.
Nicoll and Arnold describe an anencephalous fetus with absence of
spinal marrow; and Smith also records the birth of an amyelitic fetus.

In some persons there are exaggerated curvatures of the spine. The
first of these curvatures is called kyphosis, in which the curvature is
posterior; second, lordosis, in which the curvature is anterior; third,
scoliosis, in which it is lateral, to the right or left.

Kyphosis is the most common of the deviations in man and is most often
found in the dorsal region, although it may be in the lumbar region.
Congenital kyphosis is very rare in man, is generally seen in monsters,
and when it does exist is usually accompanied by lordosis or spine
bifida. We sometimes observe a condition of anterior curvature of the
lumbar and sacral regions, which might be taken for a congenital
lordosis, but this is really a deformity produced after birth by the
physiologic weight of the body. Figure 131 represents a case of
lordosis caused by paralysis of the spinal muscles.

Analogous to this is what the accoucheurs call spondylolisthesis.
Scoliosis may be a cervicodorsal, dorsolumbar, or lumbosacral curve,
and the inclination of the vertebral column may be to th