that active contraction of
the muscle is taking place (active muscle-sensation). The fibres of this
system run with the motor nerves, and pass to muscles, tendons, and
joints. Even division of both the ulnar and the median nerves above the
wrist produces little loss of deep sensibility, unless the tendons are
also cut through. The failure to recognise this form of sensibility has
been largely responsible for the conflicting statements as to the
sensory phenomena following operations for the repair of divided nerves.

2. Those which subserve _protopathic_ sensibility--that is, are capable
of responding to painful cutaneous stimuli and to the extremes of heat
and cold. These also endow the hairs with sensibility to pain. They are
the first to regenerate after division.

3. Those which subserve _epicritic_ sensibility, the most highly
specialised, capable of appreciating light touch, _e.g._ with a wisp of
cotton wool, as a well-localised sensation, and the finer grades of
temperature, called cool and warm (72-104 F.), and of discriminating
as separate the points of a pair of compasses 2 cms. apart. These are
the last to regenerate.

A nerve also exerts a trophic influence on the tissues in which it is
distributed.

The researches of Stoffel on the minute anatomy of the larger nerves,
and the disposition in them of the bundles of nerve fibres supplying
different groups of muscles, have opened up what promises to be a
fruitful field of clinical investigation and therapeutics. He has shown
that in the larger nerve-trunks the nerve bundles for special groups of
muscles are not, as was formerly supposed, arranged irregularly and
fortuitously, but that on the contrary the nerve fibres to a particular
group of muscles have a typical and practically constant position within
the nerve.

In the large nerve-trunks of the limbs he has worked out the exact
position of the bundles for the various groups of muscles, so that in a
cross section of a particular nerve the component bundles can be
labelled as confidently and accurately as can be the cortical areas in
the brain. In the living subject, by using a fine needle-like electrode
and a very weak galvanic current, he has been able to differentiate the
nerve bundles for the various groups of muscles. In several cases of
spastic paralysis he succeeded in picking out in the nerve-trunk of the
affected limb the nerve bundles supplying the spastic muscles, and, by
resecting portions