650 
DR. T. L. BRUNTON AND MR. W. PTE ON THE ACTION 
between the beats of the heart when these have become slow, either from the action of 
the drug or from irritation of the vagus-trunk. 
In order to ascertain whether this contraction was due to the action of the drug upon 
the vasomotor centre in the medulla oblongata or in the vessels themselves, the vaso- 
motor centre in the medulla was separated from its connexion with the vessels by divi- 
sion of the spinal cord in the neck previous to the injection of casca. 
Effect on Blood-pkessure after division of Cord. 
Experiment XLII. — May 17. 
A large strong cat, weighing 7^ lb., was chloroformed. A cannula was inserted into 
the left carotid, and another into the jugular vein. The spinal cord was then divided 
opposite the second cervical vertebra, and artificial respiration kept up. 
Time. 
Blood- 
pressure. 
Pulse in 
10 sec. 
Oscilla- 
tions. 
m. s. 
0 0 
Condition after section of cord and previous to injec- 
tion of casca 
millims. 
80 
25 
millims. 
5 
0 3 l 
0 7 J 
Injected 1 cub. centim. watery solution of casca. 
0 10 
80 
25 
5 
0 20 
130 
18 
12 
0 30 
140 
13 
20 
0 40 
150 
1.3 
25 
0 50 
150 
18 
12 
1 0 
175 
28 
5 
1 10 
190 
32 
4 
1 20 
200 
34 
3 
1 30 
210 
34 
3 
1 1 40 
220 
41 
4 
2 0 

230 
44 
3 
2 10 

Sudden alteration in character of pulse, which becomes 
slow. The curve flat-topped, and both systole and 
diastole showing numerous secondary oscillations. 
Rlood-pressnre falling 
190 
31 
40 
2 20 
180 
2 
5 
30 
2 40 
165 
6 
25 
3 0 
Blood-pressure rapidly falling 
130 
6 
15 
3 20 
Both pulse and oscillations are very irregular ...... 
100 
5 
9 
3 40 
80 
3 50 
25 
4 0 
10 
There was no more pulsation after this; but the 
blood-pressure took T 30" to fall quite to zero. 
On opening the thorax the heart was found moderately 
contracted; electrical stimulation of the phrenic 
nerve caused contraction of the diaphragm. 
The result of this experiment will be seen all the more clearly by the followin 
diagram, in which they have been graphically represented. 
be 
