REPRODUCTION 39 



twisted like corkscrews. They are very active in movement, 

 and dart back and forth across the field of a microscope so 

 swiftly that they can hardly be followed by the eye. The move- 

 ment is apparently by wave motions passing through the body, 

 often accompanied by a rotation of the body in corkscrew fashion. 

 Swiftly moving spirochsetes show many small waves in their 

 bodies, while the more slowly moving ones have larger and more 

 graceful curls. They also have the power of bending their 

 bodies to and fro, and of oscillating while attached to some object 

 by one end. Spirochsetes ordinarily divide by a transverse 

 division of a single thread into two; a spirochsete in the act of 

 such division can be seen in Fig. 6. The result of growth in 

 length and transverse division is that the spirochsetes of any 

 given species are very variable in size. Often individuals can 

 be found which have incompletely divided and which hang to- 

 gether in long chains. Another interesting method of repro- 

 duction in spirochsetes, the details of which have been worked out 

 largely by Fantham and his students, is by " granule-shedding,' 7 

 i.e., the production of tiny granules by a breaking up of the 

 body substance inside the delicate enclosing membrane into a 

 chain of round " coccoid bodies," resembling coccus forms of 

 bacteria (Fig. 4). These minute bodies are set 

 free either by a disintegration of the enclosing 

 membrane or by a rupture of the latter at 

 one end. The elongation of the granules, the 

 taking on of the sinuous form and the ultimate 

 development of diminutive spirochsetes are said 

 by several investigators to have been observed 

 by them in living cultures of these organisms. 

 It is probable that the granule-shedding occurs 

 at regular periods in the life of spirochaetes, 

 and that it is comparable to the process of FIG. 4. Spirochceta 

 sporulation in malarial parasites. It appears to duttoni, showing 

 be particularly associated with the existence in P rocess of granule 



the intermediate host if there is one, but it formation and 



ding. (After Fan- 



also occurs in the blood of the vertebrate host, t h am .) 

 sometimes apparently in preparation for the 

 transfer to the intermediate host, sometimes as a protection 

 against adverse conditions. It is quite likely that some spiro- 

 chsetes may be able to resist atmospheric drying up while in 



