144 



ELECTRICITY AND PROTOPLASM 



[Ch. VI 



creased, however, this .spiral becomes shorter, i.e. has more 

 turns per centimeter of progression from one pole to the other 



Fig. 37. — Form of the path of Paramecium under different conditions, a, when not 

 subjected to the constant current ; b, when subjected to a slight current ; u, when 

 subjected to a still stronger one. (From Ludloff, '95.) 



(Fig. 37), until at 60 S, in making one turn of the spiral, the 

 organism progresses hardly more than its own length. 



Finally, the effect of the current 

 upon the movement of the cilia must 

 be considered.* In the resting Para- 

 mecium the cilia rise perpendicularly 

 from the surface of the body (Fig. 38). 

 If an individual stands with its ante- 

 rior (blunt) end towards the anode, 

 and a current of 8 S passes through, 

 the cilia at the posterior (kathode) 

 end begin to vibrate. If the individ- 

 ual lies transverse to the current and 

 the current is closed, the cilia on the 

 kathode side vibrate, those on the 



anode side being quiet. With a cur- 

 ing position of cilia when . t -la ^ j-i, j. ii, i j.i 



unstimulated. The blunt rent ot lb 8 one can see that the kath- 

 (From ode Stimulation increases the forward 

 (anteriad) phase of the cilium move- 

 ment (the "recovery"). With an intensity of 24 8, vibration 

 of cilia occurs at both kathode and anode. It is, however, more 



* LuDLOFF was enabled to make a careful study of the effect of the current 

 on the cilia Ijy making use of gelatine solutions such as have been recommended 

 by Jensen ('93, p. 556). 



Fig. 38. — Paramecium, show- 



end is anterior. 

 LUDLOFF, '95.) 



