38 
MORBID ANATOMY. 
The following summary of the post-mortem appearances of the 
disease are based on the findings in seven cases from the Bitter Root 
Valley. 
Rigor rnortis. — Usually intense and appears early. 
Skin. — Jaundiced, sometimes deeply. One or more wounds appar- 
ently caused by tick bites usually present. The skin has a marbled 
appearance, well shown by the cut on page 23. On the non-dependent 
parts of the body spots, petechial in character, from bright red to 
dark purple in color and from 1 to 3 cm. in diameter: most abundant 
on wrists, ankles, arms, and back. The capillaries are congested; 
minute extravasation in the rete extending into the stratimi mucosum. 
SServov-s system . — The cerebral and spinal meninges are normal 
except for slight hypostatic congestion. Xo increase in fluid. The 
brain and spinal substance normal. 
Respiratory organs. — Pleurae normal and do not contain excess of 
fluid. Lungs show hypostatic congestion: occasionally pneumonia. 
Circidatory system. — ^Pericardium normal. A few small petechial 
hemorrhages under the epicardium over left ventricle were constantly 
found. The heart muscle is flabby, softened, and pale. Right heart 
full of blood: left, contracted and empty. The nuclei are faintly 
stained: libers granular and fragmented. 
Digestive organs. — Stomach normal. Small and large intestines 
normal in appearance throughout: Peyer's patches rather pale in color, 
^lesenteric and retroperitoneal glands not enlarged. Spleen iisaally 
dark purple in color, soft, diffluent, and from three to four times its 
normal weio-ht: vessels engoro-ed with blood: manv mononuclear leu- 
oocytes containing from one to four red corpuscles: no free pigment. 
Liver enlarged, fatty, and in portions areas outlined by bile pigment; 
sections usually show an advanced degree of fatty infiltration: bile 
capillaries full. Pancreas about' twice its normal weight. 
Kidneys. — Enlarged: capsule usually not adherent. Small subcap- 
sular hemorrhages on ventral surface. On section, congested and 
swollen cortex: pyramids well outlined and deep red color. Small 
hemorrhages in pelvis. Microscopically there are minute extravasa- 
tions of blood in cortex and under the capsule: veins filled with blood. 
Nuclei of the convoluted tubules stain poorly: cells granular and in 
some places detached: newly formed casts in tubules. Bladder normal 
and usually with small amount of dark urine. 
PROGNOSIS. 
Of 121 cases which have occurred in or near the Bitter Root Valley. 
81 died, giving a case mortality,. of about 70 per cent.' The mortality 
varies within narrow limits from vear to vear. some vears as manv as 
