48 
made in normal saline, or in glycerine fol- 
lowed by dilution with normal saline, and 
usually the fresh gland was employed. The 
experiments differed from those reported by 
others, in that extracts were made sepa- 
rately of the glandular and the infundibu- 
lar lobe, and the physiological effects of 
each were tested by injection into the cir- 
culation of normal dogs. It was found that 
the extracts of the glandular lobe have lit- 
tle or no perceptible effect when injected 
alone. Extracts of the small infundibular 
lobe, on the contrary, have a distinct and 
remarkable effect upon the heart-rate and 
blood pressure, an effect which resembles 
in some respects and differs in others from 
that shown by suprarenal extracts. 
Briefly stated, these extracts injected into 
the normal animal with its vagi intact 
cause a very pronounced slowing of the 
heart-beat, similar to that caused by su- 
prarenal extracts, but lasting a much longer 
time. The heart-beat is not only slowed, 
but is considerably augmented in force, as 
is shown by tracings taken with a Hurthle 
manometer. At the same time the blood 
pressure rises to a considerable extent, 
owing, apparently, to a peripheral constric- 
tion of the blood vessels, since oncometric 
tracings from the kidney show that this 
organ shrinks greatly in volume. Usually 
the constriction of the blood vessels occurs 
first, so that the pressure rises for about 20 
mms. or more more of mercury. This is 
succeeded sometimes by a temporary fall of 
pressure during which the heart-rate may 
be increased, and then the slowing of the 
heart begins, while the pressure rises again 
to a greater or less extent above the nor- 
mal. This last effect continues for a rela- 
tively long time and passes off gradually. 
The slowing of the heart may continue for 
half an hour or longer. If the dose used is 
a maximal one, and a second injection is 
given too quickly afterward, little or no 
effect is obtained. If, however, the dose is 
SCIENCE. 
[N. 8. Vou. VI. No. 132. 
not too strong, and sufficient time is given 
given for its action to wear of, arepetition of 
the effects is obtained, and this may occur 
a number of times, although the effects de- 
crease progressively in intensity. 
The effects of the injection are somewhat 
different if the vagi are previously cut, or 
if a little atropin is given to paralyze the 
inhibitory fibres. Under these cireum- 
stances the slowing of the heart-rate is very 
much less marked, although not entirely 
lacking. In round numbers it may be said 
that with the vagi intact the heart-rate is 
reduced about 50 per cent., while in the 
atropinized animal the reduction is about 
20 per cent. It might be added that an 
animal deeply under ether alone behaves 
in this respect like an animal with its vagi 
cut. This result indicates that the slowing 
of the heart-rate in the normal animal is 
due in part, but only in part, to a direct 
action on the medullary centers of the in- 
hibitory fibres. On the other hand, the 
rise of blood pressure after section of the 
vagi is greater. Usually the blood pres- 
sure rises rapidly for about 20 mms. of 
mercury ; this is succeeded in some cases 
by a temporary fall, and then the pres- 
sure again rises rapidly, reaching a height, 
in some cases, nearly equal to that 
caused by suprarenal extracts. During 
this last phase the heart-beats are slower 
and more powerful, the effect in this re- 
spect differing from that caused by su- 
prarenal extracts. The effect lasts longer 
than with suprarenal extracts, and a longer 
interval must be allowed before a new in- 
jection will give the same result. I have 
obtained a marked rise of pressure from 
injection of extracts of the infundibular 
lobe, after severance of the cord below the 
medulla, and in one case after removal of 
most of the thoracie part of the spinal 
cord in addition, thus indicating that the 
constriction of the blood vessels is prob- 
ably a peripheral effect, and not due to 
