The Modes of Division of Spirochasta recurrentis, etc. 



501 



each other s observations. As a result; we believe that we have arrived at a 

 solution of the difficult problem of the mode of division of Spirochetes. 



Material and Methods. 



The blood of tame mice infected with Spirochceta duttoni and S. recurrentis 

 (Kussian variety) was used as the source of the Spirochetes. The prepara- 

 tions of freshly drawn peripheral blood were transferred at once to the stage 

 of a microscope enclosed in a thermostat kept at blood temperature (37° C). 

 In this way the Spirochsetes could be observed for many hours. 



At other times, for purposes of comparison, no thermostat was used, 

 and the preparations were examined at room temperature. Freshly drawn 

 blood from the heart, liver, spleen, and kidneys of infected mice was also 

 examined. The objectives used were Zeiss' 2 mm. apochromatic homogeneous 

 immersion, or Zeiss' -jV" achromatic, with compensating ocular 8. 



Careful observations were also made on living Spirochceta, anodontce, in 

 order to determine whether there is a uniformity in the methods of division 

 in the Spirochsetes of mammalian blood, and in the Spirochetes occurring in 

 the crystalline styles of Laruellibranchs. Thin portions of infected styles 

 from Anodonta cygnea were examined, the preparations being kept at the 

 temperature of the room. Other portions of infected styles were allowed to 

 dissolve in water, and preparations were made. Living specimens of 

 S. anodontce were under observation for as long as 50 hours. 



Longitudinal Division. 



Longitudinal division of >S'. duttoni and S. recurrentis is best seen when the 

 blood under examination contains relatively few Spirochetes. We have 

 found such to be the case at the onset of the infection. At this time there 

 are but few Spirochaetes in the blood, and their movements can be followed, 

 though it is at all times a difficult task. As the number of Spirochsetes 

 during the early stages of infection is few, the danger of confusing longi- 

 tudinal division with entanglement figures is at a minimum. This possible 

 source of error has been carefully considered and eliminated. 



The Spirochsetes about to divide longitudinally are slightly thicker than 

 the other forms, and are somewhat slower in their movements. At the 

 onset of division, waves resembling the peristaltic waves seen travelling along 

 the intestine of an insect begin to pass down the body of the Spirochsete. 

 These waves were carefully differentiated from the spirals of the body of the 

 parasite. A split appears at one end of the organism, and two distinct free 

 ends are seen. The undulations continue to pass down the body, each free 

 part having its waves vibrating in unison with the other. As the length of 

 vol. lxxxi. — b. 2 o 



