403 
(1) The character of this depends very largely upon the 
method of injection, the rapidity of fall being directly as the 
rapidity of introduction into the blood. 
The blood-pressure continues lower for two or three hours— 
the longest time during which any experiment was carried on. 
It may be lowered to a very considerable extent, less than one- 
half. 
The fall is largely due to dilatation of the small blood- 
vessels, since 
(a) After injection of Atropin the blood-pressure does not 
rise though the slowing of the heart is removed. 
(b) After injection of Atropin the blood-pressure is still 
further reduced by a fresh injection of J aborandi, though the 
heart-beat rate remains the same. 
(c) When the Jaborandi is carefully and slowly injected, 
the tracing of the fall of blood-pressure is not recognisable from 
that obtained by stimulation of the central end of the De- 
pressor. 
The fact that after the blood-pressure has been very con- 
siderably lowered by Jaborandi, stimulation of the central end 
of the depressor gives a further lowering, points to its being due, 
not to a central paralysis of the vaso-motor centre, but to some 
local action ; moreover Jaborandi causes dilatation in the blood- 
vessels of the Frog’s web after section of the sciatic. 
(2) The slowing is not due to a stimulation of the cardio- 
inhibitory centre, since it takes place in the Frog after com- 
plete destruction of the brain and spinal cord, and in the Frog 
after section of both vag. 
In the Frog there is an increased susceptibility to inhibition 
of the heart by vagus stimulation after givmg Jaborandi. 
With a moderate dose and after some time, stimulation of 
the sinus venosus still produces inhibition, though with a larger 
dose, and after some time, it no longer does. 
Atropin removes the slowing rapidly and effectually, the 
