THE SPIROCHETES 157 



(/) Bacteriologists comment on the large size of S. balbianii. 

 But S. anodontce is much smaller, and S. obermeieri is smaller 

 still. Little importance is to be attached to size alone. 



Prowazek (7) mentions that 5. gallinarum may occur for a 

 time inside a red blood corpuscle of the fowl, and that this 

 characteristic is against the parasite being a Bacterium. I have 

 seen S. balbianii and S. anodontce penetrate epithelial cells of the 

 gut wall of the Lamellibranch and be attached to shed epithelial 

 cells in the alimentary tract. But these are more or less 

 accidental, and there does not appear to be a true or definite 

 intra-cellular stage in the life-history of any Spirochete. 



A few words may be written now concerning some of the 

 pathogenic Spirochetes, though fuller accounts (e.g. Blanchard, 

 1) from the pathological side should be sought in various 

 medical journals. 



S. obermeieri, the pathogenic agent of European relapsing 

 fever, is spread by bed bugs. This organism probably needs 

 re-investigation, for, according to Novy, it belongs to the genus 

 Spirillum. The species was founded by Cohn in 1875, having 

 been first notified by Obermeier in 1873. It is from 15/4 to 40^ 

 in length, and pointed at both ends. 



S. gallinarum, found in the blood of fowls, is the pathogenic 

 agent of relapsing fever in those birds, and is spread by fowl 

 ticks of the genus Argas. Borrel has described this organism 

 as possessing lateral or peritrichal cilia, while Prowazek (7) 

 describes it as an undoubted Spirochaete with an undulating 

 membrane. Prowazek's account is probably the more correct, 

 and the so-called cilia of Borrel are myoneme fibrils from a 

 frayed or ruptured membrane. Vies' observations (14) on 

 S. balbianii are thus explained. 



S. anserina occurs in the blood of geese. 



5. duttoni is the pathogenic agent of tick fever, especially 

 prevalent in the Congo State. It has been investigated by 

 workers at the Liverpool School of Tropical Medicine (2). It is 

 from 13/u. to 43/A long. It is spread by ticks, and the Spirochetes 

 find their way into the ova of ticks, thus infecting the progeny 

 of the latter. Dutton and Todd (3) quite recently have described 

 both longitudinal and transverse fission in this form (as in 

 S. balbianii), and the presence of an undulating membrane, as 

 suggested by the present writer (5, p. 34, footnote). 



S. dentium occurs in the human mouth, and is very small. 



