142 DYNAMICS OF LIVING MATTER 



1 80 and point toward the cathode. The tentacles at the cathode 

 end become more crowded together, reminding one of the tip of a 

 moistened paint brush, and also point more directly toward the cathode. 

 The experiment may be varied in still other ways by cutting smaller 

 or larger pieces from the edge of the swimming bell, but the response 



is always the same. 



The tentacles, wher- 



4- HJ jjBg,, ever possible, and to 



FIG. 29. -AFTER BANCROFT. a less extent the 



manubriurn, bend so 



as 10 point toward the cathode. The response depends in no way 

 upon the connection of these organs with the swimming bell, muscles, 

 or nerve ring, for it is obtained equally well with isolated tentacles 

 and pieces of tentacles. Isolated tentacles when placed transversely 

 to the current lines curve so as to assume a more or less complete 

 U -shape, with their concave side toward the cathode. When placed 

 parallel to the current, the tentacles do not curve" (Fig. 30). The 

 latter observation shows very nicely the fact that the whole reaction 

 is due merely to an increase in the tension of the muscles on the 

 cathode side of the organ. 



We are dealing here with the galvanotropic reactions of sessile 

 organs where the whole reaction is merely a galvanotropic curvature. 

 Wherever the current affects 

 the locomotive organs of a free- 

 swimming animal, besides the 

 galvanotropic orientation of the 

 animal, a swimming either 

 toward the cathode or anode 

 must occur.' As an example, 

 the reaction of an Infusorian, 

 Paramtfcium, may be quoted. 

 Verworn observed that Para- 

 mcecium, when put into a trough 

 through which a galvanic cur- 

 rent passes, is oriented in such FIG. 30. AFTER BANCROFT. 

 a way as to put its oral pole 



toward the cathode. It swims in this orientation toward the cathode.* 

 The mechanism of this reaction was discovered by Ludloff.f The 

 locomotion of Paramcecium is brought about by cilia. As a rule, 

 these cilia are directed backward (A, Fig. 31), and therefore their 



* Verworn, Pfliiger's ArcMv, Vol. 45, p. I ; and Vol. 46, p. 267, 1889. 

 t Ludloff, Pfluger's Archiv, Vol. 59, p. 525, 1895. 



