150 THE SIGNS OF LIFE [LECT. vin. 



released when that influence is removed, and manifests itself in 

 a kationic discharge from the previously anodic surface. Thus 

 we have a post-anodic action current which is of the same direc- 

 tion as that of the previous (polarising) current. 



Blaze-currents of which such frequent mention has been 

 made in these lectures are an effect of local intensifications of 

 electrolytic solution-pressure of kationic pressure when their 

 direction is from the excited spot ; of anionic pressure when 

 their direction is towards the excited spot. 



This is hypothesis which, whether or no it " explains " all 

 the known facts, at least neither contradicts nor obscures them ; 

 it seems to me to bring them under a common denomination, 

 and to invite us to their further investigation. Hypothesis is 

 the mother of experiment. 



REFERENCES 



ENGELMANN. "Ueber das Vorkommen und die Innervation von con- 

 tractilen Driisenzellen in der Froschhaut," P finger's Archiv, iv., p. i, 

 1871. 



ENGELMANN. "Ueber die electromotorischen Krafte der Froschhaut, 

 ihren Sitz und ihre Bedentung fiir die Secretion," PfliigeSs Archiv, 

 iv., p. 321, 1871. 



ENGELMANN. "Die Hautdriisen des Frosches," Pfliiger's Archiv, v., 

 p. 498, 1872, and vi., p. 97, 1872. 



MACDONALD. "The Injury Current of Nerve," Thompson Yates Labora- 

 tories Report, vol. iv., part ii., 1902. 



BIEDERMANN. Elektrophysiologie, Jena, 1895 ("Action of Water and of 

 Saline Solutions on Mucosa Currents," p. 401.) 



LOEB. " Physiologische Untersuchungen tieber lonenwirkungen," PfliigeSs 

 Archiv, Ixix., p. i, 1898, and Ixxi., p. 457. 



