600 
SECOND REPORT -1832. 
sisting on the necessity of extreme caution in forming theories 
from the indications even of the best microscopes. 
His account of the physiological phenomena attending the 
respiration of oxygen and other gases, is chiefly derived from 
his own researches. In this inquiry, rabbits, kittens, guinea- 
pigs, mice, sparrows, and frogs, were subjected to the influence 
of the gases in glass jars containing one and two gallons. 
It was found that animals immersed in oxygen gas lived longer 
in it than in an equal quantity of atmospheric air ; that the re¬ 
sidual gas still consisted principally of oxygen ; and w r as capa¬ 
ble of maintaining the respiration of a second animal, as long as 
on the first trial. Very little carbonic acid gas w r as produced 
in the jar of oxygen, even by the repeated respiration of seve¬ 
ral successive animals. The average period during which the 
warm-blooded animals remained unaffected by pure oxygen, 
was about one hour, the cold-blooded much longer. The im¬ 
mersion of kittens and rabbits in this gas was usually attended 
with apparent death in about three hours, but they were some¬ 
times brought to life again by artificial respiration, and if the 
action of the diaphragm had not quite ceased, even by simple 
exposure to the open air, with warmth ; debility, however, su¬ 
pervened in these cases, and occasionally death ; if the dia¬ 
phragm had ceased to act, there was no recovery, though the 
heart had not ceased to beat. Rabbits, however, in some in¬ 
stances survived longer in the gas : one remained seven hours 
in the two-gallon jar, apparently unaffected, and at the expira¬ 
tion of 13 hours was not dead. The first symptoms of failing 
life were gasping, hurried respiration, panting, and strong ac¬ 
tion of the heart; then follow ed a stage of increasing debility 
and decreasing sensibility, the animal falling on its side, draw¬ 
ing deep and slow inspirations, w ith short expirations, at longer 
and longer intervals, until a glaziness of the eyes and absence 
of all motion indicated total insensibility. Examined in this 
state, the diaphragm was still, but the heart in action, and 
the peristaltic motion of the viscera maintained. The heart, 
after being removed, continued for some time to contract on 
being irritated. In all the examinations, the bright crimson 
colour of the interior of the animal arising from the action of 
oxygen upon the blood, whether the animal had breathed in 
fresh oxygen, or was the second or third in succession in the 
same jar of gas, was very remarkable. The author terminates his 
description of these effects of oxygen gas by stating his opinion, 
that oxygen, pure or in excess above the proportion in atmo¬ 
spheric air, acts as a poison and produces on the animal system 
effects very analogous to those of narcotic or sedative poisons. 
