ie 
i. 
wee 
| 
i 
Le 
ON THE PHYSIOLOGICAL ACTION OF MEDICINES. 29 
with it, might not produce any very marked effect. In an experiment per- 
formed with selenic acid, the following are the symptoms that presented 
themselves (the acid used was of specific gravity 1046, containing about five 
and a half per cent. of real acid). On injecting three drachms of the acid, 
mixed with an equal quantity of water, into the jugular vein, no appreciable 
effect was produced ; neither the passage of the blood through the lungs, nor 
through the systemic capillaries, appeared at all impeded ; nor was the action 
of the heart affected ; in about forty-five seconds after the injection its move- 
ments appeared slightly fluttering; after two minutes the respiration was 
observed to be rather deeper. Immediately after the introduction of half an 
ounce of the acid into the vein, there was a falling off of the quantity of 
blood sent into the arterial system; and as this took place five seconds after 
the injection, it must have been owing to the passage of the blood through 
the pulmonary capillaries having been impeded, for there had not been time 
for the substance to reach the coronary arteries and act on the heart. After 
thirty seconds the supply of blood to the arteries was restored, and the action 
of the heart was as strong as before. There appeared to be no marked effect 
produced on any organ, although the quantity of acid introduced was very 
considerable (seven drachms) ; after a few minutes the respiratory movements 
became longer and deeper, and the action of the heart decidedly weaker, the 
force with which the blood was propelled into the arteries being only half 
what it is in the natural state of the circulation ; there was no expression of 
pain. Half an ounce of the acid was again injected into the veins. The 
immediate effect was to arrest the passage of the blood through the lungs, no 
blood being sent into the arteries, although the heart could be felt beating 
through the parietes of the thorax. Respiration was stopped at a minute 
and twenty seconds after the arrest of the circulation, sensibility having dis- 
appeared a few seconds earlier, On opening the thorax immediately after the 
cessation of respiratory movements, the heart was found beating rythmically : 
the right cavities were very much distended with blood, which was dark and 
grumous, and apparently physically incapable of passing through the lungs. 
The left cavities contained a small quantity of scarlet blood, which was co- 
agulated ; the lungs were redder than natural; the heart retained its irrita- 
bility some time after death. The above symptoms-do not suffice to indicate 
_ any particular organ on which the acid exerts a marked influence; for although 
death was produced by the passage of blood through the pulmonary ca- 
‘pillaries being arrested, yet this was probably owing to the mechanical 
impediment which the coagulated state of the blood must have opposed to 
its passage through the pulmonary vessels. In other experiments that I have 
made with this substance, I have sometimes seen a serous secretion take place 
in the air passages. There is also some action on the nervous system, as the 
following experiment will show. The animal was small ; it was not confined, 
in order that the effects on the functions of voluntary motion and sensation 
might be more accurately observed. A drachm of the acid was introduced 
into the veins, without giving rise to any marked symptoms. A second in- 
jection, containing a drachm and a half of the acid, did not affect the animal 
in any marked degree: after a few minutes it appeared rather dull, but there 
was no expression of pain, nor was sensibility impaired. On introducing 
two drachms into the veins, the animal fell down in about thirty seconds, and 
respiration was much affected ; it got up again in about a minute, and jumped 
about ina very curious manner, the movements being evidently involuntary, 
as if the animal had chorea: it remained standing quite motionless for a few 
“minutes, but gradually became weaker, and death took place ten minutes 
after the last injection; there were no convulsions, nor was the sensibility 
