416 Proceedings of the Royal Society of Edinburgh. [Sess. 
produced. Small doses tend to produce a diastolic type of change, and 
large doses a systolic type. This applies equally to application of 
8. sarmentosus to the outer surface of the heart and to its administration 
through the blood-stream. 
With small quantities the rate of the heart’s contractions is slowed, and 
the size of the diastolic as well as of the systolic movements of the 
ventricles and auricles, and the strength of the systolic contractions of 
both, are increased. These changes are produced when a dilution of even 
1 in 500,000 is perfused through the frog’s heart. The slowing of the 
heart’s rate is partly due to this increased range of movement, but lengthen- 
ing of the diastolic pause plays an important part in the retardation. 
With large quantities, the heart’s contractions may, at first, be modified 
in the same way as with small quantities, but the diastolic expansions of 
the ventricles afterwards become reduced, the quantity of blood entering 
them becomes lessened, and the ventricles finally cease to contract and 
remain motionless in extreme systole. Previously to the final standstill, 
the ventricular pulsations are usually limited to small portions of its wall. 
Paralysis of the vagus by atropine, after the cardiac effects have been 
developed, does not modify these effects, nor does paralysis of the vagus, 
before and during the administration of the extract, prevent the occur- 
rence of the changes in the heart which are characteristic of the action of 
Strophanthus. 
The cardio-inhibitory function of the vagus nerve is not increased or 
otherwise appreciably modified by 8. sarmentosus. 
On the blood-vessels, the action of the extract is slight, for very strong 
solutions cause only an unimportant degree of contraction. 
8. sarmentosus does not appear to affect the blood-pressure, excepting 
through the changes produced in the heart’s contractions. No evidence 
was obtained of a haemolytic or a blood-clotting effect, in vivo. 
The lymph hearts of the frog are practically unaffected by this 
substance. 
The chief effects on the respiration are attributable to the action on the 
heart, though there may also be a direct action on respiration through its 
medullary centre. 
The spinal reflex disappears a considerable time after the administration 
of lethal doses of the extract, and only after the heart and respirations have 
been much affected. This disappearance is due not only to reduced blood- 
supply, but also to a direct action on the cord. 
When applied to the skin of frogs, the extract is capable of temporarily 
abolishing the function of sensory nerves in strong solutions, such as from 
