s material;
but the salivary glands by irritative sympathy are thrown into similar
action, and produce an infectious saliva similar to that instilled into the
wound.

Though in many contagious fevers a material similar to that which produced
the disease, is thus generated by imitation; yet there are other infectious
materials, which do not thus propagate themselves, but which seem to act
like slow poisons. Of this kind was the contagious matter, which produced
the jail-fever at the assizes at Oxford about a century ago. Which, though
fatal to so many, was not communicated to their nurses or attendants. In
these cases, the imitations of the fine vessels, as above described, appear
to be imperfect, and do not therefore produce a matter similar to that,
which stimulates them; in this circumstance resembling the venereal matter
in ulcers of the throat or skin, according to the curious discovery of Mr.
Hunter above related, who found, by repeated inoculations, that it would
not infect. Hunter on Venereal Disease, Part vi. ch. 1.

Another example of morbid imitation is in the production of a great
quantity of contagious matter, as in the inoculated small-pox, from a small
quantity of it inserted into the arm, and probably diffused in the blood.
These particles of contagious matter stimulate the extremities of the fine
arteries of the skin, and cause them to imitate some properties of those
particles of contagious matter, so as to produce a thousandfold of a
similar material. See Sect. XXXIII. 2. 6. Other instances are mentioned in
the Section on Generation, which shew the probability that the extremities
of the seminal glands may imitate certain ideas of the mind, or actions of
the organs of sense, and thus occasion the male or female sex of the
embryon. See Sect. XXXIX. 6.

4. We come now to those imitations, which are not attended with sensation.
Of these are all the irritative ideas already explained, as when the retina
of the eye imitates by its action or configuration the tree or the bench,
which I shun in walking past without attending to them. Other examples of
these irritative imitations are daily observable in common life; thus one
yawning person shall set a whole company a yawning; and some have acquired
winking of the eyes or impediments of speech by imitating their companions
without being conscious of it.

5. Besides the three species of imitations above described there may be
some associate motions, which may