SPIROCH^ETES : RESISTANT FORMS 75 



the spirochaete begin to concentrate around the 

 chromatin bars (Fig. 20, A , B), and thus a number 

 of segments are formed within the spirochaete, whose 

 periplast acts as a sheath. The further concentration 

 of the cytoplasm (Fig. 20, C, D), gives rise to a 

 number of small oval or rounded bodies, sometimes 

 termed " spores " or " granules " (Fig. 20, D). Some- 

 times these small spores lie transverse to the long 

 axis of the spirochaete ; at other times they may be 

 slightly curved and lie obliquely. The result re- 

 sembles a series of biconvex or rounded tabloids 

 within a thin skin. Ultimately, the periplast rup- 

 tures at one end (Fig. 20, E), and the small bodies, 

 which for convenience we term "spores," issue into 

 the food-canal. These spores or coccoid bodies 

 (Fig. 20, F) are probably able to withstand con- 

 ditions unfavourable to the spirochaetiform stage of 

 the parasite. It has been suggested that coccoid 

 bodies or spores are degeneration products. De- 

 generating spirochaetes have a very different appear- 

 ance from those forming spores, and, further, de- 

 generating members do not reproduce a new and 

 vigorous race of spirochaetes as do the spores. The 

 spore develops into a spirochsete by the same series 

 of changes as does the corresponding form of a blood- 

 spirochaete, and will be described in detail there. 



The function of the spores is, obviously, to serve 

 as a means of transference to a new host. But 

 among molluscan spirochaetes, cross-infection with 

 mature spirochaetes by the direct agency of water 

 has been shown. Apparently clean Tapes aureus, 

 placed in water containing oysters known to be 



