176 DR. A. D. WALLER OR THE ELECTROMOTIVE CHARGES 
is convenient to allncle to these two phases as the major phase and the minor phase 
respectively. 
In the diagram, fig. 3, o . . . o denotes the iso-electric state of two led-off points, A 
and B; the ordinate o — denotes the maximum negativity of B manifested imme¬ 
diately after injury ; the line —t denotes the gradually declining negativity of B. 
I. represents a normal diphasic variation. 
1 st phase, A negative. 2nd phase, B negative. 
II. represents a monophasic variation after injury of B ; unbalanced negativity 
of A. 
III. and IV. represent diphasic variations re-appearing as the negativity of B 
declines. 
1 st phase, A negative (major phase). 
2 nd phase, B negative (minor phase).- 
The facts of experiment are in complete agreement with this theoretical representa¬ 
tion. With a normally beating heart in situ, led off from the apex to the mercury of 
the electrometer, from the base to the sulphuric acid, the level of the mercury in 
the capillary showed that apex and base were iso-electric in the intervals between 
the beats, each of which was accompanied by the double variation SN, signifying :— 
1 st phase, apex negative. 
2 nd phase, base negative. 
The base was now injured by crushing with forceps ; on re-applying the eleclrode to 
the injured base, the mercury in the capillary came to rest in the diastolic period 
much nearer the end of the capillary [i.e., North in the field of the microscope), 
indicating iiegativity of the base ; each beat was now accompanied by a single 
variation S, indicating negativity of the apex. Ten minutes later the mercury had 
subsided South (indicating declining negativity of the base); each beat was now 
accompanied by a variation S?^, signifying:— 
1 st phase, apex negative (major phase). 
2 nd phase, base negative (minor phase). . 
Ten minutes later the variation was still diphasic ; but tlie 1st phase had diminished, 
while the 2nd pljase had increased. 
The changes accompanying the subsidence of injury negativity do not always follow 
the above regular form; in some cases the heart dies so rapidly that spontaneous 
beats giving the double phase do not re-appear, though mechanical excitation may still 
be capable of producing a contraction marked by a double phase ; in other cases the 
double phase re-apjDears at first in an intermittent manner, most beats being still 
