648 
DE. T. L. BEUNTON AND ME. W. PTE ON THE ACTION 
In this experiment, as well as in several others, the blood-pressure rose without being 
accompanied by a slowing of the pulse, and this indicates that the latter is not dependent 
on the former. 
The excitability of the vagus-roots to reflex stimuli does not seem to be increased by 
casca, as a stimulus of the same strength applied to the central end of one vagus had a 
similar effect before and after the injection of the drug. We would call attention, 
however, to the very extraordinary effect which succeeded the application of a stronger 
stimulus, an effect which seems all the more extraordinary from occurring after the 
stimulus had ceased, and not during its application. 
Irritation of the vagus-roots by the carbonic acid accumulated in the blood during 
the tetanic inspiration, which lasted during the irritation, at once suggests itself as a 
cause of the slow pulse which followed the irritation ; but the fact that the pulse was 
not affected when the distance of the coil was 10 centimetres, although the thorax was 
tetanically expanded, seems to indicate that the slowing which followed the stronger 
irritation from a secondary coil at 8 or 6 centimetres distance from the primary was 
due to reflex action, which the first irritation had been too weak to produce. 
From Experiment XXXV. it will be seen that after the administration of a large 
dose of casca, irritation of the vagi, instead of producing slowing or stoppage of the 
heart’s action increased the frequency of its pulsations. The acceleration was equally 
great after irritation of the left, as after irritation of the right vagus. This shows that 
the accelerator-fibres in the vagus are not paralyzed by casca, and also that accelerator- 
fibres, though usually, according to Boehm, contained only in the right vagus, may 
occasionally be present in the left. 
The effect of irritating the other accelerating nerves of the heart contained in the 
rami cardiaci or in the sympathetic cord was not examined. 
Action on Cardiac Ganglia, Effect on Pulse, etc. 
Experiment XXXVIII. — June 10. 
A moderate-sized cat was chloroformed, and cannulse were placed in the carotid artery 
and jugular vein. 
A solution of 3 cub. centirns. of saturated alcoholic tincture added to 50 cub. centims. 
of water was used for injection into the vein. 
Time. 
Blood- 
pressure. 
Oscilla- 
tions. 
Pulse in 
10 sec. 
m. s 
millims. 
millims. 
25 
0 5 
1 20 
Condition before injection 
Injected 1 cub. centim. casca solution. 
160 
23 
1 30 
Condition shortly after injection 
Rise of blood-pressure, slowing of pulse. 
180 
50 
14 
2 0 
Later, quickening of pulse 
165 
7 
26 
3 0 
Same effect, more marked 
175 
5 
36 
4 0 
Commencing slowing of pulse 
170 
6 
30 
4 30 
„ „ „ 
140 
8 
30 
5 0 
5 5 
Further injection of 1 cub. centim. casca. 
150 
14 
24 
5 40 
Secondary slowing of pulse with fall of blood-pressure. 
115 
25 
16 
