300 THE ELECTROCARDIOGRAM 



doubt the wave of negativity produced by the contraction of the 

 ventricles and S is the second phase or positive reaction. The 

 space between S and T represents the time during which the whole 

 ventricle is excited, and T probably indicates the arrival of the 

 wave of negativity at the apex. Other interpretations have been 

 given. 



It has been suggested for ease in analysis, that it is advisable to 

 compound the records from all three leads into one diagram. This 

 so-called monocardiogram represents the algebraic sum of all the 

 potential differences at every point of the cardiac cycle. 



