RELATIONS OF SPIRILLUM TO THE DISEASE 500 



remained alive and virulent in defibrinated rats' blood for forty 

 days. He also succeeded, by Levaditi's method (p. 516), in 

 obtaining cultures in collodion sacs containing rats' blood which 

 were placed in the peritoneum of rats. By this method cultures 

 were maintained for many generations ; the organisms were still 

 virulent though the resulting infection was rather less intense 

 than at first. The spirochjetes are readily killed at a tempera- 

 ture of 60 C., but may be exposed to C. without being 

 killed. Novy [and Knapp have found that there is a single 

 nagellum at one end of this organism. 



Relations to the Disease. In relapsing fever, after a period 

 of incubation there occurs 

 a rapid rise of tempera- 

 ture which lasts for about 

 five to seven days. At 

 the end of this time a 

 crisis occurs, the tempera- 

 ture falling quickly to 

 normal. In the course of 

 about other seven days a 

 sharp rise of temperature 

 again takes place, but on 

 this occasion the fever 

 lasts a shorter time, again 

 suddenly disappearing. A 

 second or even third re- 

 lapse may occur after a 

 similar interval. The 

 organisms begin to appear 

 in the blood shortly before 

 the onset of the pyrexia, 



and during the rise of temperature rapidly increase in number. 

 They are very numerous during the fever, a large number being 

 often present in every field of the microscope when the blood is 

 examined at this stage. They begin to disappear shortly before 

 the crisis : after the crisis they are entirely absent from the 

 circulating blood. A similar relation between the presence of 

 the organisms in the blood and the fever is found in the case of 

 the relapses. Munch in 1876 produced the disease in the 

 human subject by injecting blood containing the spirochsetes, 

 and this experiment has been several times repeated with the 

 same result. Additional proof that the organism is the cause of 

 the disease has been afforded by experiments on animals. Carter 

 in 1879 was the first to show that the disease could be readily 



FIG. 152. Spirochaetes of relapsing fever in 

 human blood. Film preparation. (After 

 Koch.) See also Plate IV., Fig. 18. 

 x about 1000. 



