JULY 9, 1897. ] 
tions of life it might not exist. Fortunately, 
we have direct proof that the active sub- 
stance in question is a normal product of 
the metabolism in the gland. Cybulski 
and Szymonowicz found that blood drawn 
from the suprarenal vein, when injected 
into the circulation of a normal animal, 
gives the same effect, although less in 
amount, as extracts of the suprarenal 
glands, while blood from other veins has 
no such action. This result has been de- 
nied by Oliver and Schafer, apparently 
upon insufficient experimental grounds. 
Langlois,* on the contrary, has been able 
to corroborate this effect of suprarenal 
blood, and, in the laboratory at Baltimore, 
Dr. Dreyer has obtained clear proof of a 
similar action. It appears from Dreyer’s 
experiments that the effect is not obtained 
in every animal, but in some cases the re- 
sults are very positive, and in a matter of 
this kind the positive evidence is the most 
important. When we remember that we 
are dealing most probably with a material 
formed by the secretory activity of gland 
cells, and that the amount of this material 
may vary at different times or under dif- 
ferent circumstances, it is not surprising 
that negative as well as positive results are 
obtained. 
Since it seems certain that the substance 
does occur under normal conditions in the 
venous blood flowing from the gland, we 
are justified in concluding that it is a nor- 
mal product of the metabolism of the medul- 
lary cells of the gland, and that it is dis- 
charged or secreted directly into the blood. 
It must, therefore, exert continually a stimu- 
lating effect upon the heart and blood ves- 
sels. In corroboration of this last conclu- 
sion we have some striking experiments re- 
corded by Szymonowicz which show that 
after complete extirpation of the two glands 
the blood pressure becomes greatly de- 
* Langlois: Archives de Physiologie normale et 
pathologique, 152, 1897. 
SCIENCE. 
45 
pressed. Both Oliver and Schafer, and 
Cybulski and Szymonowicz, conclude that 
the normal function of the suprarenals con- 
sists in furnishing this stimulating sub- 
stance to the blood. The former observers 
believe that its effect is mainly upon the 
muscular tissue ; that it has a general tonic 
or augmenting action on all varieties of 
muscle found in the body—the striated 
muscle as well as the cardiac and plain 
muscle tissue. Cybulski and Szymonowicz 
hold essentially the same general view, ex- 
cept that they believe that the substance 
acts upon the nerve centers controlling the 
muscular tissues rather than on these tis- 
sues directly. It is, perhaps, impossible at 
present to decide as to this detail. Oliver 
and Schafer have shown, without much 
doubt, that the substance acts upon the 
blood vessels after their connections with 
the central nervous system have been com- 
pletely severed, and, on the other hand,there 
is clear proof that it affects at least one 
part of the central nervous system, namely, 
the cardio-inhibitory center. Further ex- 
perimenting will probably soon furnish more 
definite information upon the extent to 
which the muscular and the nervous tissues 
are affected by this substance. Upon either 
of the views proposed we can understand 
at once why removal of the suprarenals 
brings on a condition of muscular asthenia, 
and why the continual activity of these or- 
gans is so essential to the body as a whole. 
It is significant, in this connection, to recall 
that Oliver and Schafer found that extracts 
of the suprarenals in cases of Addison’s 
disease did not contain this stimulating 
substance. The hypothesis that the supra- 
renals secrete a stimulating substance that 
augments the tone of the muscular system, 
either directly or indirectly, is not the only 
one offered to explain the physiology of 
these bodies. According to some observers 
the main function of the suprarenals, like 
that of the thyroids, is to produce an anti- 
