190 
DR. A. D. WALLER ON THE ELECTROMOTIVE CHANGES 
sition that it passes in a straight line from end to end of the organ. I do not, 
however, attach much importance to this estimate, having regard to the nature of the 
data and suppositions involved. The initial point of the second phase, which is pre¬ 
sumably the indication of declining negativity of the apex, occurs about second 
after the initial point of the first phase. The interval between the initial point 
and the maximum of the second phase is about second. 
I regard these time relations as an indication that the contraction, while beginning 
at the apex, lasts longest at the base. 
It has been suggested to me, as possible, that the contraction of the entire heart, 
commencing at the venous orifices of the auricles, is propagated thence by the auriculo- 
ventricular curtains and musculi papillares to the apical vortex, and thence upwards 
to the base of the ventricles. This is a speculation for or against which I can at 
present see no positive evidence. 
Photo. 5. 
-1-1-1-1-1— -1-1-1- 1 Time in sec. 
Enlargement ( x 6) of a single systole of photo. 4, to show :— 
I. First phase n (apex negative). II. Second phase S (base negative), 
r, c cardiogram ; e, e = electrometer line. 
