cal Features.#--The symptoms resulting from division and non-union
of a nerve-trunk necessarily vary with the functions of the affected
nerve. The following description refers to a mixed sensori-motor trunk,
such as the median or radial (musculo-spiral) nerve.

_Sensory Phenomena._--Superficial touch is tested by means of a wisp of
cotton wool stroked gently across the skin; the capacity of
discriminating two points as separate, by a pair of blunt-pointed
compasses; the sensation of pressure, by means of a pencil or other
blunt object; of pain, by pricking or scratching with a needle; and of
sensibility to heat and cold, by test-tubes containing water at
different temperatures. While these tests are being carried out, the
patient's eyes are screened off.

After division of a nerve containing sensory fibres, there is an area of
absolute cutaneous insensibility to touch (anaesthesia), to pain
(analgesia), and to all degrees of temperature--_loss of protopathic
sensibility_; surrounded by an area in which there is loss of sensation
to light touch, inability to recognise minor differences of temperature
(72-104 F.), and to appreciate as separate impressions the contact of
the two points of a compass--_loss of epicritic sensibility_ (Head and
Sherren) (Figs. 91, 92).

_Motor Phenomena._--There is immediate and complete loss of voluntary
power in the muscles supplied by the divided nerve. The muscles rapidly
waste, and within from three to five days, they cease to react to the
faradic current. When tested with the galvanic current, it is found that
a stronger current must be used to call forth contraction than in a
healthy muscle, and the contraction appears first at the closing of the
circuit when the anode is used as the testing electrode. The loss of
excitability to the interrupted current, and the specific alteration in
the type of contraction with the constant current, is known as the
_reaction of degeneration_. After a few weeks all electric excitability
is lost. The paralysed muscles undergo fatty degeneration, which attains
its maximum three or four months after the division of the nerve.
Further changes may take place, and result in the transformation of the
muscle into fibrous tissue, which by undergoing shortening may cause
deformity known as _paralytic contracture_.

_Vaso-motor Phenomena._--In the majority of cases there is an initial
rise in the temperature of the part (2 to 3 F.), with redness and
increased