thra.
3. ---- _ductus choledoci._ ---- of the bile-duct.

* * * * *

CLASS II.

DISEASES OF SENSATION.

ORDO I.

_Increased Sensation._

GENUS I.

_With Increased Action of the Muscles._

The actions belonging to this genus are those which are immediately excited
by the sensations of pain or pleasure, but which are neither followed by
inflammation, nor by convulsion. The former of which belong to the
subsequent genera of this order, and the latter to the class of voluntary
motions.

The criterion between the actions, which are the immediate consequence of
painful sensation, and convulsive actions properly so called, consists in
the former having a tendency to dislodge the stimulating cause, which
induces the painful sensation; and the latter being exerted for the purpose
of expending the sensorial power, and thus dulling or destroying the
general sensation of the system. See Class III. 1.

There is a degree of heat produced in the affected part by these sensitive
actions without inflammation, but in much less quantity than when attended
by inflammation; as in the latter there is a production of new vessels. See
Sect. XXXIII. 2. 3.

Some of the species of this genus cannot properly be termed diseases in
their natural state, but become so by their defect or excess, and are here
inserted to facilitate the explanation of the others.

SPECIES.

1. _Deglutitio._ Swallowing our food is immediately caused by the
pleasureable sensation occasioned by its stimulus on the palate or fauces
and is acquired long before the nativity of the animal. Afterwards the pain
of hunger previously produces the various voluntary exertions to procure
the proper material, but the actions of masticating and of swallowing it
are effected by the sensorial power of sensation; which appears by their
not being always controulable by the will, as when children in vain attempt
to swallow nauseous drugs. See Class IV. 1. 3. 1. The masticated food
stimulates the palate, which is an organ of sense, into so much action, as
to produce agreeable sensation; and the muscles subservient to deglutition
are brought into action by the sensation thus produced. The pleasureable
sensation is the proximate cause; the action of the fibres of the
extremities of the nerves of taste is the remote cause; the sensorial power
of irritation exciting these fibres of the nerves of taste into increased
action is the pre-remote ca