JULY 9, 1897. ] 
during this period, a great fall in blood 
pressure, together with a feeble heart-beat. 
Tt will be noted that in cases of Addison’s 
disease in man the important symptoms, in 
addition to the pigmentation, are also an 
asthenic condition of the muscles and the 
heart. What explanation have we to offer 
for the surprisingly profound effect pro- 
duced upon the body by the removal of 
these small organs ? 
Unquestionably, the most significant facts 
with regard to this problem have been ob- 
tained from a study of the effects of injec- 
tions of suprarenal extracts into living ani- 
mals. A number of the earlier experiments 
of this kind, especially those performed upon 
rabbits, resulted in the death of the animal, 
the preceding symptoms being convulsive 
movements, followed by some paralysis. 
The really valuable results, however, have 
been obtained by a more exact study of the 
effects of such injections upon the vascular 
and respiratory organs. Most of our knowl- 
edge upon these points has been derived 
from the researches of Oliver and Schafer, 
and Cybulski and Szymonowicz.t These 
two sets of investigators published their re- 
sults nearly simultaneously. The impor- 
tant facts determined by them, and since 
corroborated in many laboratories, are as 
follows: Extracts of the medulla of the su- 
prarenal bodies injected into the veins of a 
living animal cause a pronounced slowing of 
the heart-beat and a large rise of blood pres- 
sure. If the animal is first given atropin to 
paralyze the inhibitory nerves to the heart, 
or if the vagi are previously cut, the injection 
causes usually a marked quickening, instead 
of a slowing of the heart-beat, and a greater, 
indeed often an extraordinary, rise of blood 
*Oliver and Schafer : Journal of Physiology, XVIILI., 
1895. 
{ Cybulski and Szymonowiez: Gazeta Lekarska, 
1895. (Abstracted in Jahresb. d. Thier-Chimie, 
1895. Also Szymonowiez: Archiv. fiir d. gesammte 
Physiologie, LXIV., 1896. 
SCIENCE. 
43 
pressure. The respiratory organs are not 
affected so seriously, a temporary slowing 
and shallowing of the respiratory move- 
ments being the result usually noticed. The 
effect upon the heart and blood vessels is 
quite temporary. Its exact duration de- 
pends somewhat upon the dose, and in part 
upon other less evident conditions, but, as 
a rule, within a very few minutes the rise 
in blood pressure, as well as the slowing of 
the heart-beat, passes off completely. New 
injections will bring out promptly a return 
of the effect described, although a continued 
repetition of the injections at too close inter- 
vals results in a progressive diminution of 
their action. Tying off the kidneys does 
not appear to prolong the effects of an injec- 
tion, so that we may conclude that the tem- 
porary character of the result produced is 
not caused by a rapid elimination of the 
active substance through the kidneys, al- 
though, according to Szymonowicz, a part of 
it, at least, is got rid of by this means. The 
rapid disappearance, however, of the effects 
of a maximal or supramaximal dose indi- 
cates that the active substance is either 
quickly destroyed in the tissues or is neu- 
tralized in some unknown way. 
The physiological explanation of the 
slowing of the heart caused by the suprarenal 
extracts offers no difficulties. Since this 
effect disappears completely upon section of 
the vagi, or after the injection of a few 
milligrams of atropin, it can only be due to 
a stimulating action upon the central end- 
ings of the inhibitory fibres, that is, upon 
the so-called cardio-inhibitory center in the 
medulla. According to Oliver and Schafer 
the inhibitory effect is felt mainly upon the 
auricles. The beats of this part of the heart 
become weaker and slower and may cease 
altogether, while the ventricular beats, al- 
though slower, are more vigorous. After 
the vagi have been cut, suprarenal extracts 
cause a quicker and, according to Oliver 
and Schafer, who measured the extent of 
