Book II PESTILENT FEVERBS 87

rence, for he assigned as the cause moisture that has been con—
traeted and is the predisposing factor.

These fevers, moreover, differ from other putrid fevers in the
nature of their accidents. For they have the power to carry
on the contagion to another person, and the only cause that can
be assigned for this is the make—up (character) of the germs,
which when carried to another person produce in that second
body something of just the same sort as was in the first affected.
But if a pestilent fever arises in us originally, we can never
say that it is pestilent until the germs of contagion have al—
ready been developed. "Therefore it is fair to say that the fever
has been caused by germs, and is adapted to arise from those
germs and to contain them per se.

If, then, we permit ourselves to define pestilent fever, we shall
say:— It is a fever of foul and deep—seated putrefaction; 4£ contains
germs of the most acute contagion, per se; hence it is a deadly disease,
and is contagious for another person. 'This, then, and not putre—
faction of the heart or its contents, is the essential characteris—
tic of a pestilent fever. Not that there is any reason why the
putrefaction should not be carried to them, also, especially if
there exists an analogy between them and the putrefaction.
But whether this be the case or not, it is not the essential charac—
teristic of the plague, though perhaps it is characteristic of a
more violent form of plague which is more quickly fatal. But
the thing that is essential and as they say formal, is that it is a
fever which contains in itself the germs of death—dealing con—
tagion. For these reasons, fevers that are caused by poisons,
though deadly, are not pestilent, since they are not contagious.
For they lack that formal and essential characteristic of the

plague.