PATHOGENIC SPIRILLA. 591 
In experiments made by Heydenreich the spirillum was found to 
preserve its vitality (motility) for fourteen days at a temperature of. 
Fie. 170.—Spirillum Obermeieri in blood of maa. x 1,000. From a pbotomicrograph.. 
(Frankel and Pfeiffer. ) 
16° to 22° C., for twenty hours at 37°, and at 42.5° for two or three 
hours only. 
Pathogenesis.—Causes in man the disease known as relapsing 
fever. Miinch and Moczutkowsky have produced typical relapsing: 
Fic. 171.—Spirillum Obermeieri in blood of an inoculated ape. x 700. (Koch. 
fever in healthy persons by inoculating them with blood containing 
the spirillum of Obermeier. The spirilla are found in the blood dur- 
ing the febrile paroxysm, and for a day or two, at the outside, after 
