BOOK II
CONTAGIOUS DISEASES

CHAPTER I
coxTAGIOUS FEVERS

The natural sequel to the preceding Book is a discussion, one
by one, of the contagious diseases that are known to us, their
nature, the causes that produce them, and how they differ from
one another. I will begin with those contagious diseases &
knowledge of which seems to be most urgently needed. Of
this sort are the fevers that consist in contagion, and these
I must discuss the more carefully because several of them, of
a novel and unusual type, have appeared in our generation.
Generally speaking, very little, considering their importance,
was written about any of thesefevers by our ancestors. I shall
assume for the present discussion that we know what the word
&ever! means, used in the ordinary sense, and how fever arises.

I do not call 'contagious' all fevers that can infect a neigh—
boring and contiguous bodily humor, but only those which
have power to transmit to another a precisely similar infection,
and which contain in themselves what I have called germs of
contagion. Among contagious fevers, some kinds are called
(pestilent', others 'non—pestilent'. Again, among the pestilent
kinds, some are 'simply pestilent', while others are only called
'(malignant', being as it were, something between the pestilent
and the non—pestilent.  Some contagious fevers are mostly salu—
tary, others most!y fatal; others again, are now salutary,
now fata!, and from them many recover, though many die,
and it is not certain whether more die or recover, for example
in fevers of the sort called lenticulae'.

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