1908. | Innervation in Vaso-motor Reflexes, ete. 367 
doses of chloroform in the “dilator” animal, as due to inhibition of dilator 
| tone. 
The first curve of fig. 25 shows the ordinary result of exciting the median 
nerve in the eviscerated rabbit under ether; rise of blood-pressure and 
constriction of the limb of which the dilators had been cut. Chloroform was 
then given in as great an amount as possible without lethal results; the 
blood-pressure fell by 70 mm. Hg. Excitation of the median still gave a rise 
of pressure, but now accompanied by dilatation of the limb. This means that 
the process which previously resulted in excitation now results in inhibition. 
At the same time there are too few constrictors left in the body to counteract 
by their inhibition the opposite effect on the blood-pressure of the inhibition 
Fig. 25.—Inhibition of constrictor tone by excitation of a pressor nerve under chloro- 
form, etc. Upper curves in each, volume of hind-limb, vaso-dilators}icut. 
Lower curves, arterial pressure. Zero different for each. 
of dilators present as a normal constituent of the reflex and left intact by the 
chloroform, which apparently only attacks excitation processes in such a way 
as to reverse them, while inhibitory processes are unchanged in sign until 
finally paralysed. The result is that a rise of blood-pressure occurs, produced, 
not by excitation of constrictors, but by inhibition of dilator tone. The third 
curve was obtained after return to ether anesthesia and partial recovery, the 
arterial pressure having risen by 25 mm. Hg. Excitation of constrictors is 
commencing to return as a part of the reflex from median nerve. 
The result of this experiment shows the incorrectness of a statement made 
by me in a former paper to the effect that the depressor reflex from sensory 
nerves under chloroform differed from the true one from the depressor nerve 
