78 SPIROCTLETES. 



at regular intervals; sometimes the bars may exist 

 separately without the connecting band (Figs. 7, 60). 



Multiplication takes place by longitudinal division, 

 and may be very rapid in suitable conditions, giving 

 rise to the appearance of very attenuated individuals, 

 scarcely visible under the microscope. Divi- 

 sion of the undulating membrane precedes 

 that of the body of the organism. When 

 fission is nearly complete, the daughter 

 individuals remain attached by a strand of 

 periplast for some time, appearing as a single 

 individual of abnormal length with a thin 

 portion in the middle. In the process of 

 division the nucleus first condenses to form a 

 straight rod, lying in the central axis of the 

 animal. This rod breaks up into short 

 segments, shaped first like bacilli and then as 

 dumb-bells; these are next broken up into 

 little spherical masses, which take up posi- 

 tions in two rows and finally in groups of 

 four. Perrin believes that the total number 

 of these is sixty-four. When fission has oc- 

 Spirochseta curr ed and the new individuals are formed, 

 balbianii. the nucleus of each reforms a spiral band. 



(Schellack.) ^ ^ 1 , e 



Encystment takes place by a senes of 

 movements by which the two ends of the spirochaete 

 first travel alternately up and down its length, and then 

 the whole organism rolls up into a coil (Fig. 41). The 

 periplast then bursts, and the entoplasm escapes, tak- 

 ing a spherical form, but not secreting any covering 

 membrane. 



The female forms are described as larger and stouter, 

 with a thicker periplast. They have a smaller undulat- 

 ing membrane, and encyst less readily. The nucleus 

 goes through a somewhat different course of changes in 



