disease, and has a very appreciable ability to resist antiseptic agents.
If the germ of syphilis were equally hard to kill, syphilis would be an
almost universal disease. Fortunately it dies at once on drying, and is
easily destroyed by the weaker antiseptics provided it has not gained a
foothold on favorable ground. Its inability to live long in the presence
of air confines the source of infection largely to those parts of the
body which are moist and protected, and especially to secretions and
discharges which contain it. Its contagiousness is, therefore, more
readily controlled than that of tuberculosis. It is impossible for a
syphilitic to leave a room or a house infected for the next occupants,
and it is not necessary to do more than disinfect objects that come in
contact with open lesions or their secretions, to prevent its spread by
indirect means. Such details will be considered more fully under the
transmission and hygiene of the disease.

+Mode of Entry of the Germ.+--The germ of the disease probably gains
entrance to the body through a break or abrasion in the skin or the
moist red mucous surfaces of the body, such as those which line the
mouth and the genital tract. The break in the surface need not be
visible as a chafe or scratch, but may be microscopic in size, so that
the first sore seems to develop on what is, to all appearances, healthy
surface. It should not be forgotten that this surface need not be
confined to the genital organs, since syphilis may and often does begin
at any part of the body where the germ finds favorable conditions for
growth.

+Incubation or Quiescent Period.+--Almost all germ diseases have what is
called a period of incubation, in which the germ, after it has gained
entrance to the body, multiplies with varying rapidity until the
conditions are such that the body begins to show signs of the injury