714 THE BLOOD-INHABITING SPIROOELETES 



microscopical examination no spirochsetes could be found was infective for 

 rats. 



The blood was diluted with 10 parts of citrated normal saline solution and filtered 

 through new Berkefeld bougies under a pressure of 50 pounds. 



Kepeating these experiments with S. duttoni, Breinl and Kinghorn once 

 or twice produced a mild infection in rats. 



SECTION II. MORPHOLOGY AND METHODS OF DETECTION. 

 1. Microscopical appearance and staining reaction. 



Blood should be obtained by pricking the finger. A number of blood 

 films should be spread and dried ready for staining, and a drop of blood 

 should also be examined in the fresh unstained condition. 



The examination of fresh blood. If a drop of blood be taken during an 

 attack of fever and examined fresh under the microscope, numerous spirochsetes 

 will be seen lying between the red cells of the blood, 8-10/x long, very slender 

 and pointed at their ends, each showing six to fifteen spirals. They are 

 highly motile and scattering the red cells as they go move in a straight line 

 either in an oscillatory manner or with a cork-screw-like motion. The 

 spirochsetes tend to agglutinate and form rosettes in the blood of persons 

 suffering from relapsing fever (fig. 342). Very long organisms are sometimes 

 seen measuring perhaps 100/x from end to end ; these appearances are really 

 due to the fact that several individuals have become attached to one another 

 end to end. 



FIG. 341. Spirochceta recurrentis. Blood film. (Oc. 2, obj. T \th, Zeiss.) 



It is said that the movements observed in spirochsetes are due to flagella which 

 stain only with difficulty, and four flagella have been described arranged in bunches 

 of two at each end of the parasite. Zettnow using a modification of Borrel's method 

 (vide S. marchouxi) has described a peritrichial structure surrounding the S. 

 duttoni the flagella being inserted all over the surface of the spirochsete. Novy 

 and Knapp have not been able to demonstrate lateral flagella but describe a long 

 single undulating flagellum in S. recurrentis attached to one end of the organism : 

 in Breinl's opinion this is merely a prolongation of the periplast. [According to 

 Nuttall, " authors who claim that spirochsetes possess flagella have been led into 

 error by the study of stained specimens of macerated spirochaetes, these having been 

 rendered quite abnormal in appearance through the partial stripping off of their 

 outer layer or periplast, the myonemes forming the pseudo-flagella. ] 



