44 
the contractions directly, a stronger beat. 
This accelerating effect upon the heart after 
removal of the inhibitory fibres is not due, 
aS we might at first suppose, to a stimula- 
tion of the central ends of the accelerator 
fibres, since it is still obtained after section 
of the cord in the neck, or after extirpation 
of the first thoracic ganglia. It must, 
therefore, be due to a peripheral action of 
the extracts upon the heart itself, either 
upon the muscle of the heart directly (Oliver 
and Schafer) or upon the so-called motor 
ganglia (Szymonowicz, Gottlieb). 
The effect of the injections upon blood 
pressure has been explained differently by 
those engaged in the work. Both Oliver and 
Schafer, and Cybulski and Szymonowicz, 
believe that the enormous rise in blood 
pressure is due mainly to a great constric- 
tion of the arterioles. According to the 
latter this constriction is brought about by 
a stimulating action of the extracts upon 
the vaso-motor centers in the medulla and 
cord, while according to Oliver and Schafer 
the action is exerted directly on the muscles 
of the blood vessels. Szymonowicz admits 
that if the cord is cut just below the medulla 
a great rise of pressure can still be obtained, 
but he explains this by supposing that the 
extract acts on the spinal centers. He as- 
serts that if the entire cord is destroyed a 
rise of pressure can no longer be obtained. 
The experiment that he gives to illustrate 
this last point is, however, far from being 
convincing. The protocol of the experiment 
shows that the act of destroying the cord in 
itself reduced the blood pressure to zero. 
Moreover Biedl* reports that he has been 
able to get a rise in pressure from injection 
of the extracts after complete extirpation 
of the cord. The evidence, therefore, seems 
to favor the view proposed by Oliver and 
Schafer, and this view is still further sup- 
ported by the fact that when the volume of 
a limb is measured plethysmographically it 
*Bied]: Wien. klin. Wochenschrift, IX., 196. 
SCIENCE. 
[N. S. Vou. VI. No. 132. 
often shows a distinct diminution after 
suprarenal injection, even though its nery- 
ous connections with the central nervous 
system are entirely severed. 
There are, however, some facts reported 
in the experiments made by different ob- 
servers which indicate that the assumed 
action of the substance on the peripheral 
arteries does not alone account for all the 
changes produced in blood pressure. It 
is probable that the greater force of the 
heart-beat plays an important part, as 
Gottlieb* contends, in causing the increase 
of arterial tension. Thus Szymonowicz 
reports measurements of the pressure in 
the external jugular vein made during one 
of his experiments. According to this re- 
port the venous pressure rose and fell with 
the arterial pressure, which is not what 
one would expect to occur in the case of a 
general constriction affecting the arterioles 
alone. According to Bayliss and Hill,; 
also, the general venous pressure increases 
with the rise in arterial pressure. So ina 
number of the published tracings given by 
Oliver and Schaffer it appears that the 
vaso-constriction was more pronounced in 
the abdominal viscera than in the limbs, 
since the volume of the latter measured 
plethysmographically showed an increase 
of a passive character, apparently, while 
the volume of the kidney or spleen was 
greatly diminished. 
The significance of the marked reaction 
exhibited by suprarenal extracts depends 
very largely upon the possibility of proving 
that the substance producing the reaction 
is formed normally within the gland. It 
is conceivable, of course, that in the dead 
gland post-mortem changes might cause 
the formation of a substance giving this re- 
action, although under the normal condi- 
* Gottlieb : Archiy f. exper. Pathologie u. Phar- 
makologie, XX XVIII., 1897. 
{ Bayliss and Hill: Journal of Physiolology, XVIII. 
Pp 352, 1895. 
