746 Proceedings of Royal Society of Edinburgh. [sess. 
and to tliis fluid a certain dose of Strophanthus was added. The 
apparatus further recorded the individual contractions of the heart, 
so as not only to show the rate of contraction, hut also the ampli- 
tude of each contraction. With very minute doses, and in the 
early stages of the action of larger doses, the contractions became 
slower, and an increased volume of fluid was projected from the 
heart at each contraction. It was found that when the circulating 
fluid contained Strophanthin in the proportion of one part in ten 
millions, the characteristic changes were produced. Even the almost 
inconceivably minute dose which was brought in contact with the 
heart when a solution of one in six millions was used, produced com- 
plete stoppage of the heart, in extreme systolic contraction, in less 
than half an hour. One 'part in fifteen millions , one part in eighteen 
millions , and even one part in tiventy millions also produced well- 
marked effects ; but these extreme dilutions did not always arrest the 
heart’s contractions, and, as contrasted with the changes produced 
by less dilute solutions, the slowing of the heart was due to delay 
during its diastole more than during its systole. 
When the exposed heart is observed in situ after the administra- 
tion of Strophanthin, even when the dose is only a minimum lethal 
one, the changes that are seen are usually those indicating a great 
increase in the strength and in the duration of systolic contraction, 
and the ultimate standstill of the heart is, as before described, 
brought about by the systolic contraction becoming persistent and 
passing immediately into rigor mortis. This increased duration of 
contraction, with consequent lessening of the dilatation of the heart 
and of the capacity of its chambers, is not, however, the action 
which is likely to be serviceable in weak conditions of the organ or 
in the existence of disabling lesions. 
I accordingly made some experiments in which Strophantin was 
given in rather less than minimum lethal doses — in some experi- 
ments by subcutaneous administration, and in others by direct appli- 
cation of a solution to the heart’s surface. When care was taken 
to prevent any irritant, even the air in motion, from reaching the 
heart, a minute dose produced slowing and a great increase in 
the amplitude of dilatation, with strong systolic contractions. In 
some experiments the diastolic pause was so greatly lengthened that 
the heart remained motionless for two or three minutes, with its 
