action
after their temporary quiescence; as kibed heels after walking in snow.

4. But when these new motions of the vascular muscles are exerted with
greater violence, and these vessels are either elongated too much or too
hastily, a new material is secreted from their extremities, which is of
various kinds according to the peculiar animal motions of this new kind of
gland, which secretes it; such is the pus laudabile or common matter, the
variolous matter, venereal matter, catarrhous matter, and many others.

5. These matters are the product of an animal process; they are secreted or
produced from the blood by certain diseased motions of the extremities of
the blood-vessels, and are on that account all of them contagious; for if a
portion of any of these matters is transmitted into the circulation, or
perhaps only inserted into the skin, or beneath the cuticle of an healthy
person, its stimulus in a certain time produces the same kind of morbid
motions, by which itself was produced; and hence a similar kind is
generated. See Sect. XXXIX. 6. 1.

6. It is remarkable, that many of these contagious matters are capable of
producing a similar disease but once; as the small-pox and measles; and I
suppose this is true of all those contagious diseases, which are
spontaneously cured by nature in a certain time; for if the body was
capable of receiving the disease a second time, the patient must
perpetually infect himself by the very matter, which he has himself
produced, and is lodged about him; and hence he could never become free
from the disease. Something similar to this is seen in the secondary fever
of the confluent small-pox; there is a great absorption of variolous
matter, a very minute part of which would give the genuine small-pox to
another person; but here it only stimulates the system into common fever;
like that which common puss, or any other acrid material might occasion.

7. In the pulmonary consumption, where common matter is daily absorbed, an
irritative fever only, without new inflammation, is generally produced;
which is terminated like other irritative fevers by sweats, or loose
stools. Hence it does not appear, that this absorbed matter always acts as
a contagious material producing fresh inflammation or new abscesses. Though
there is reason to believe, that the first time any common matter is
absorbed, it has this effect, but not the second time, like the variolous
matter above mentioned.

This acco