GENERAL CHARACTERS OF SPIROCILETES. IQ 



spiculifera) . Certainly this form tends to be shorter 

 on the average than the form with blunt extremities; 

 but some overlapping may occur, and it seems prema- 

 ture to make a specific division on this ground alone 

 (see page 81). 



Movements. The movements of the large spirochaetes 

 are very rapid under normal conditions, but become 

 slower as vitality diminishes. They are of three main 

 kinds: (i). Lashing movements, such as are performed 

 by an eel suspended on a hook, the whole body being 

 bent from side to side, taking the forms of a circle or an 

 S or a figure of eight. These are most evident when the 

 spirochaete is attached in some way by one extremity or 

 hindered in its progression. (2). Undulating move- 

 ments, which are compared to the flapping of a sail 

 "in the wind," a wave passing from one end of the 

 organism to the other and being rapidly succeeded by 

 other similar waves in the same direction. It would 

 seem that the direction may be reversed. (3). A rota- 

 tory movement, like that of a cork-screw when pushed 

 into a cork, the whole spirochaete turning on a longit- 

 udinal axis passing through the centres of the spirals 

 (the axis of the helix). Special forms of movement 

 are described by Perrin as taking place in the process of 

 encystment, one end of the organism gliding down the 

 side of the body, to be followed by a similar movement 

 of the other extremity, and finally by a continuous 

 movement by which the creature is rolled upon itself. 



Structure. Examined microscopically, the structure 

 of the spirochaete is seen to consist of an external coat 

 or periplast, which contains an inner protoplasmic sub- 

 stance or entoplasm. The periplast may be prolonged 

 at one or both ends of the organism into an appendage, 

 which some authors regard as a flagellum. This iden- 

 tification seems incorrect. It has also been suggested 



