XVII. 
PATHOGENIC SPIRILLA. 
SPIRILLUM OBERMEIERI. 
Synonyms.—Spirochete Obermeieri; Spirillum of relapsing fe- 
ver ; Die Recurrensspirochate. 
Discovered by Obermeier (1873) in the blood of persons suffering 
from relapsing fever. 
This spirillum is present, in very great numbers, in the blood of 
relapsing-fever patients during the febrile paroxysms. It has not 
been found under any other circumstances, and its etiological rela- 
tion to the disease with which it is associated is generally admitted. 
Morphology.—Very slender, flexible, spiral or wavy filaments, 
with pointed ends; from sixteen to forty “in length and consider- 
ably thinner than the cholera spirillum—about 0.1 4. Koch has 
demonstrated the presence of flagella (Eisenberg). 
Stains readily with the aniline colors, especially with fuchsin, 
Bismarck brown, and in Léffler’s solution of methylene blue. 
Biological Characters.—An aérobic, motile spirillum which 
has not been cultivated in artificial media. This spirillum appears to 
be a strict parasite, whose habitat is the blood of man. The disap- 
pearance of the parasite from the blood soon after the termination 
of a febrile paroxysm, and its reappearance during subsequent par- 
oxysms, have led to the inference that it must form spores, but this 
has not been demonstrated. In fresh preparations from the blood 
the spirillum exhibits active progressive movements, accompanied 
by very rapid rotation in the long axis of the spiral filaments, or by 
undulatory movements. The movements are so vigorous that the 
comparatively large red blood corpuscles are seen, under the micro- 
scope, to be thrown about by the slender spiral filaments, which it is 
difficult to see in unstained preparations. When preserved in a one- 
half-per-cent salt solution they continue to exhibit active movements 
for a considerable time. Efforts to cultivate this spirillum in artificial 
media have thus far been unsuccessful, although Koch has observed 
an increase in the length of the spirilla and the formation of a 
tangled mass of filaments. 
