RELAPSING FEVER. 333 



the animal body. In leeches that have sucked themselves full 

 of the blood of patients suffering from relapsing fever, and have 

 been preserved upon ice, the spirilla remained alive for ten days. 

 Little is known with regard to their temperature-relations. In 

 blood from patients suffering from relapsing fever kept in glass 

 tubes at a temperature of from 16 C. (60.8 F.) to 22 C. 

 (71.6 F.) the spirilla survive for as long as fourteen days ; at 

 a temperature of 37 C. (98.6 F.), for about twenty hours; 

 at a temperature of from 39.5 C. (103.1 F.) to 41.7 C. 

 (107.1 F.), only from four to twelve hours ; and at a tempera- 

 ture of 42.5 C. (108.5 F.), scarcely three hours (Heyden- 

 reich). Conclusions with regard to the growing bacteria in the 

 living blood can not be drawn from these observations, as the 

 blood removed from the body is no longer a favorable nutrient 

 medium for the spirilla. Nothing 

 definite is known also with regard 

 to the requirements of the spirilla 

 for oxygen. 



The relapsing spirilla can be 

 readily stained by means of watery 

 solutions of aniline dyes ; they do 

 not take acid stains. For the 

 demonstration of relapsing spirilla 

 in blood-preparations the method 

 of Giinther is useful ; this consists 

 in introducing the dried cover-slip pig 7I ._ Spirochaeta obermeieri 

 preparation, fixed by heating, be- in the blood (v. jaksch). 



fore staining with gentian- violet or 



fuchsin, for ten seconds in five per cent, acetic acid, in order to 

 extract the hemoglobin from the blood-corpuscles. The relaps- 

 ing spirilla are not so resistant as all other bacteria to the action 

 of dilute potassium hydroxid or concentrated acetic acid. In 

 their reactions they resemble the protoplasmic rather than the 

 nuclear substances. The spirilla do not stain by Gram's method. 



Occurrence of Spirilla of Relapsing Fever. The spirilla 

 are present, and in varying number, only in the blood of 

 those suffering from relapsing fever, in which they appear a 

 short time before the onset of the fever, and they undergo 

 considerable multiplication during the continuance of the 

 fever, to disappear, a short time before the critical deferves- 

 cence, until the onset of the next febrile paroxysm. 

 During the afebrile period the spirilla have been found in the 

 blood in but one case by Naunyn. They are not ordinarily 

 found in the secretions and excretions of patients suffering 

 from relapsing fever, and with equal rarity outside the 



