DISEASES CAUSED BY PROTOZOA. H9 
Infection manifests itself first by a sore called a 
chancre, which develops from three to six weeks after 
exposure. It may be located anywhere on the body, 
but is always at the point where infection entered. The 
organisms are at first localized in the primary sore, 
but very soon spread to the glands near by, and then to 
Fig. 17.—Treponema pallidum in smear from secretion of a 
fresh, hard chancre. The dark spots represent the red blood- 
cells; the light, wavy lines the spirochetes. X1000. (After 
Lenhartz .) 
the blood, causing a general infection. The result is a 
general skin eruption, sore throat, fever, and anemia,— 
symptoms that develop in from six to twelve weeks 
after the chancre, and mark the beginning of the sec¬ 
ondary stage. Later the spirochetes become localized 
in certain tissues, particularly the brain and spinal cord, 
Manifes¬ 
tation 
of the 
disease 
