66 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
Experiment No. XXI. Dog-weight 5.8 kilos. 
Time. 
Dose. 
Pressure. 
Pulse. 
Remarks. 
Cord and vagi cut. 
m. s. 
grammes. 
m. m. 
p. m. 
Cord severed between 4th and 5th cervical 
vertebrae. 
0 . 
48 
112 
15.00 
0.01 
48 
112 
Injection begun. 
.40 
50 
118 
Injection ended. 
16.30 
56 
120 
17.30 
56 
120 
• 
20.00 
... .... 
54 
118 
26.00 
28.30 
52 
48 
112 
Pulse irregular. 
32.00 
0.02 
38 
102 
Injection begun. 
32.30 
26 
92 
Injection ended. 
33.30 
20 
80 
35.00 
12 
42 
Pulse-waves large. 
38.00 
42.00 
10 
. 
30 
Pulse-waves very large. 
Heart ceased suddenly. 
Having given the details of the preceding experiments, the results of 
which have been considered in general remarks, it remains for me to dis¬ 
cuss the manner in which the various phenomena are brought about in 
regard to the circulation. 
The Pulse. —Sparteine, in small or moderate doses, causes in normal 
animals an increase in the frequency of the heart beats, followed soon 
afterward b}’ a distinct decrease of the same. 
Though not accurately determined as 3 r et, there are various ways in 
which a drug may increase the rapidity of the pulse: (a) an action on the 
heart itself, whether through stimulation of the automatic motor gan¬ 
glia, or paralysis of the intracardiac inhibitory ganglia; ( b) paralysis of 
the medullary cardio-inliibitory centers, the few accelerator fibers con¬ 
tained in the vagi remaining intact, and in this way being still able to 
convey impulses from the respective unaffected centers toward the peri¬ 
phery; (c) direct stimulation of the accelerator centers in the medulla 
oblongata through the fibers of the cervical sympathetic. 
Though by no means a constant phenomenon even in normal animals 
(both in the dog and in the batrachian), the brief period of increased 
pulse-rate under sparteine is observed in curarized animals (avoiding in 
this manner, as far as possible, any extraneous influences, especially altera¬ 
tions dependent on respiratory changes), in those in which section of both 
vagi had been previously performed, as well as in those dogs in which 
the heart was isolated from all nervous connection by previous division 
of the pneumogastrics and the spinal cord. These results and those ob¬ 
tained in the frog, appear to be concordant, and show, I think, that the 
rapidity of the pulse, when it does occur, is due to a direct cardiac action. 
