Book II RABIES 127

and finally they are exhausted and painfully breathe their
last. It is said that, if a person who has at some time in the
past been bitten by a mad dog lies down under a sorb—tree,?7
he again developes rabies.

I must therefore enquire from what causes these phenomena
arise; but I shall not make my statement on the lines of what is
called a demonstration. If I give my opinion from reasoning
and on general grounds, I must be considered to have done
enough. Since, then, this contagion is not communicated by
fomes, and is not produced in the skin by simple contaet, but
requires laceration of the skin, we must suppose that its germs?8
are not very viscous, and that they are perhaps too thick to
be able to establish themselves in pores; that they therefore
adhere to the blood only, after the slobber in which the germs
lurk has mingled with the blood. And since its progress is so
slow, it might well be supposed that the contagion is analogous
with either the solid parts of the body, such as the nerves??
and the like, or with some dense humor.  But it is well known
that in this disease, no one of the solid parts is corrupted; hence
we may conclude that the contagion is analogous with the
dense humors, I mean phlegm and black bile; this analogy seems
to be rather with black bile, since we observe that those suf—
fering from rabies finally become raving mad, just like people
who are atrabilious. Moreover, the dog itself in which the
contagion first arises, is an animal of very atrabilious and dry
temperament; again, there is in the human body a great deal
more phlegm than black bile, and this phlegm is especially prone
to putrefaction; hence, if this contagion arose in it, it would not
remain latent so long as to become manifest after the lapse of
as much as a year. On the other hand, the black bile, since it
is less abundant and is cold and dry, and so less ready to putre—
fy, is able to preserve the germs in a latent state for a longer
time.

'This contagion does not excite fever, except towards the end,
because it works very gradually, and what evaporates is not
at once carried to the heart, but only long after, or is even ex—
pelled.  But it propagates itself from one part to another till
it reaches the internal organs, and finally the praecordia.  When
it arrives there it causes fever, twitches the diaphragm and the
heart itself, and finally brings on madness and death. 'The
reason why dogs are peculiarly affected by this contagion is