GALVANOTAXIS 361 



The influence of constant currents on streaming shows no features of 

 especial importance, apart from the fact that the direction of the current 

 in no wise influences the direction of streaming, and produces no effect 

 upon the relative velocity of opposed streams l . There is, however, a special 

 physiological reaction, galvanotaxis, which may be termed positive or 

 anodic, and negative or kathodic, according to whether the responding 

 motile organisms wander towards the negative or positive electrodes. 

 Galvanotaxis appears to be shown chiefly by Infusoria, Flagellatae, and 

 Bacteria 2 , and negative galvanotaxis appears to be commoner than 

 positive. In some cases, a rise in the intensity of the currents converts 

 a positive galvanotaxis into a negative one, while some forms exhibit 

 transverse galvanotaxis. 



Negative galvanotaxis is shown by Paramaecium aurelta, P. Zwrsaria, Coleps 

 hirtus, and all the ciliate Infusoria examined, with the exception of Opalina ranarum, 

 which shows positive galvanotaxis with weak currents, but negative with stronger ones, 

 according to Wallengren. Among the Flagellatae, Verworn found Trachelomonas hispida, 

 Peridinium tabulatum to show negative, and Polytoma uvella, Cryptomonas ovata positive 

 galvanotaxis, while Chilomonas paramaedum behaves like Opalina ranarum 3 . Volvox 

 aureus shows negative galvanotaxis, according to Carlgren 4 , and possibly other 

 Volvocineae as well, although Verworn could detect no such irritability in Euglena 

 viridis*. Certain bacteria do, however, appear to have a power of galvanotactic 

 response 6 , and, according to Verworn 7 , Amoebae show negative galvanotaxis at 

 about 25C., while Schenck 8 has shown that at lower and higher temperatures the 

 galvanotaxis becomes positive. 



Transversal galvanotaxis is shown by the Infusorian Spirostomum ambiguum 9 

 and by Oxytrichia and Stylonychia while creeping on the substratum, whereas free- 

 swimming individuals show negative galvanotaxis 10 . 



The chamber shown in Fig. 64 may be used to contain the organisms to be 



1 Cf. Ewart, Protoplasmic Streaming in Plants, 1903, p. 100, and the works mentioned there. 



3 L. Hermann (Pfliiger's Archiv f. Physiologic, 1885, Bd. xxxvu, p. 457 ; 1886, Bd. xxxix, 

 p. 41 4) first observed galvanotaxis in tadpoles, and the same irritability was detected in Infusoria and 

 Flagellata by Verworn (Pfluger's Archiv f. Physiologic, 1889, Bd. XLV, p. 27; 1889, Bd. XLVI, 

 p. 268; Psycho-physiologische Protistenstudien, 1889, p. 115; Allgemeine Physiologic, 3. Aufl., 

 1901, p. 476). See also V. Ludloff, Pfluger's Archiv f. Physiologic, 1895, Bd - LIX P- 5 2 5 > J- J- Loeb > 

 ibid., 1896, Bd. LXV, p. 518; Jennings, Journal of Physiology, 1897, Vol. xxi, p. 305; Putter, 

 Archiv f. Anatom. u. Physiologic, physiol. Abth., Supplementband, 1900, p. 243; Wallengren, 

 Zeitsch. f. allgem. Physiol., 1902, Bd. n, p. 341 ; 1903, Bd. ill, p. 22. 



3 Cf. also Wallengren, 1. c., p. 377. 



* Carlgren, Centralbl. f. Physiol., 1900, Bd. XIV, p. 35. 



5 Verworn, 1. c., 1889, p. 290. Diatoms have not yet been investigated. 



6 Verworn, 1. c., 1889, p. 291 ; Chauveau, Compt. rend., 1896, T. cxxi, p. 892. 



7 Verworn, 1. c., 1889, p. 272 ; Pfluger's Archiv f. Physiol., 1896, Bd. LXV, p. 47. 



8 Fr. Schenck, Pfliiger's Archiv f. Physiol., 1897, Bd. LXVI, p. 253. 



9 Verworn, 1. c., 1901, p. 480; Pfluger's Archiv, 1896, Bd. LXII. 

 10 Putter, 1. c., p. 275. 



