88 SPIROCH^ETES. 



Nuttall suggests that he mistook the spermatozoa of 



the animal for spirochaetes (see Fig. 34). 



Sp. obermeieri is destroyed by glycerine (Gabrit- 



chewsky) . The action of a variety of different reagents 



upon these organisms was studied and tabulated by 



MacKinnon. 



Sp. obermeieri in some form or other is capable of 



passing through a Berkfeld filter. 



The spirochaetes met with in cases of relapsing 



fever in America, in Bombay and in African tick fever 

 are slightly different from the species 

 met with in Russian relapsing fever, 

 the typical form of the disease. Sp. 

 duttoni of tick fever is described be- 

 low. The spirochaete of American 

 relapsing fever (Sp. novyi) is more 

 delicate than that of the Russian 

 disease and shows more regular and 

 closely-set curls (Fig. 66) . The spiril- 



lum f Bomba 7 fever (SP- carter $ is 



thinner, less regularly curled, and 

 forms loops and "figures of 8" (Novy and Knapp). 

 Animals inoculated with one species become immune 

 to subsequent infection with this form, but not to 

 infection with the other species. 



SPIROCH^ETA DUTTONI. 



(Novy and Knapp, 1906; Breinl, 1906.) 



This organism was first discovered by Ross and Milne 

 and found independently by Button and Todd. It 

 occurs in the disease known as tick fever on the east 

 coast of Africa. Infection is conveyed by the bite of 

 the tick, Ornithodorus moubata, which exists in great 

 numbers in the huts of the natives. The spirochaete 

 is from 14 to 16/1 long, with six to seven spiral turns; 



