BIOELECTRIC PHENOMENA 331 



also be rhythmical, and if these reactions are primarily 

 those occurring in the protoplasmic surface-films, it 

 follows that rhythmical variations in metabolic activity 

 are characteristic of this region of the cell. There are 

 various general facts indicating a tendency to rhythm 

 in the activities at free cell-surfaces; for example, the 

 wide distribution of such phenomena as ciliary movement, 

 in which protoplasmic surface-processes show a regular 

 mechanical rhythm which is presumably accompanied 

 by a chemical and electromotor rhythm^. The filamen- 

 tous processes formed under certain abnormal conditions 

 from the surface of simple cells like blood corpuscles 

 also often exhibit rhythmical movements/ All such 

 movements are probably of an electro-capillary nature, 

 and referable to general conditions similar to those 

 determining the rhythmical phenomena in the poly phasic 

 inorganic systems (mercury in hydrogen peroxide, iron in 

 nitric acid) described above. As already seen, variations 

 in the structure and composition of thin interfacial films 

 are the essential factors in all such phenomena. 



The rhythmical bioelectric variations accompanying 

 the normal innervation of muscle have been investigated 

 in much detail since the application of the thread 

 galvanometer to physiological uses by Einthoven. In 

 man, Piper found the rhythmical action-currents obtained 

 from single voluntary muscles (e.g., extensor of forearm) 

 to exhibit a remarkable constancy of rhythm, of about 



* Cf. Kite, Journal of Infectious Diseases, XV (1914), 319; Oliver, 

 Science, XL (19 14), 645. 



The minute precipitation-filaments first formed when an iron wire 

 is placed in ferricyanide solution frequently exhibit rhythmical move- 

 ments of a kind suggesting ciliary movement; cf. Biological Bulletin, 

 XXXIII (1917), 139. 



