BIOELECTRIC PHENOMENA 323 



each active region excites electrically the adjoining 

 inactive region, by means of the local bioelectric current 

 accompanying activity, the velocity with which excita- 

 tion is transmitted from region to region will be higher 

 the more rapidly this current develops. Lucas' observa- 

 tion just cited shows in fact a close parallelism between 

 these two rates, in the same tissue at different temper- 

 atures. Variations in transmission-velocity in different 

 tissues, and in the same tissue under different conditions, 

 w^ould on the foregoing hypothesis have a direct causal 

 dependence on the rate of change of potential character- 

 istic of the tissue. 



Reference has already been made to the fact that 

 in each species of animal the bioelectric variations of 

 the active tissues have specific peculiarities — of rate of 

 development, normal range, duration, rhythm, etc. — 

 which exhibit a close correspondence with the peculiarities 

 of function and activity characteristic of the species. 

 For example, the normal bioelectric variation of a special 

 organ like the heart is an accurate index of the normal 

 rate and sequence of its different processes; hence, the 

 electrocardiogram may be a delicate means of detecting 

 abnormalities in the action of this organ. Presumably 

 a tracing of the bioelectric variations from the group 

 of muscles involved in the act of speech could, with 

 sufficient knowledge and analytical skill, be translated 

 into the actual words uttered. From what has already 

 been said it will be obvious that this close correspondence 

 between the functional activity of a living system and 

 the character of its bioelectric variations implies a similar 

 correspondence of both with the underlying variations 

 of metabolic activity. 



