262 ON THE INTRODUCTION OF AIR INTO THE VEINS. 
M. Magendie attributes the death of the animal to the sudden 
cessation of the circulation, in consequence of the accumulation 
of air, and its rarefaction in the cavities of the heart, u'hich it dis¬ 
tends, and to the contraction of which it opposes itself. 
M. Leroy D’Etrolles says that the air may cause death in three 
ways—by its influence on the brain, agreeably to Bichat’s opi¬ 
nion, either affecting its sensibility, or acting upon it mechani¬ 
cally ; or by its influence on the lungs, causing sudden emphyse¬ 
ma of these organs ; or by its influence on the heart, in depriving 
it of arterial blood. According to M. Picdagnel, death results 
from pulmonary emphysema. 
M. Mercier thinks that the air, by reason of its compressibility, 
yields to the contractile powers of the right cavities, and occu¬ 
pies a smaller space; but that when these cavities begin to dilate, 
the air, acquiring its former volume, fills these cavities, and pre¬ 
vents the entrance of the blood ; and thus the stagnation of the 
venous blood, and the interruption of the arterial circulation, are 
the causes of death. 
Such was the unsatisfactory state of knowledge on this ques¬ 
tion when M. Amussat undertook some new experiments. The 
commission of the Academy likewise instituted a course of experi¬ 
ments, to the number of 40. 
Twenty-nine were made on dogs, and had reference, first to the 
spontaneous introduction of air into the jugular, subclavian, and 
axillary veins; secondly, the introduction of this fluid into the 
venous vessels through the medium of a sound placed in one of 
them, and the air then introduced either by the natural expan¬ 
sion of the chest and the heart, or by artificial injection. 
In both cases the subjects of the experiments were sometimes 
placed in a horizontal and sometimes a vertical position; and in 
both the one and the other, on animals sometimes debilitated and 
sometimes not, before the experiments. 
After having stated the results of these experiments, varied in 
different ways, the reporter gives some details of the effect pro¬ 
duced by the introduction of air previously breathed and procured 
from the human chest. He concludes by stating the effect of 
various experiments, attempted with a view to prevent the fatal 
result of the introduction of the air. 
They experimented also on eleven horses, following pretty 
nearly the same courses. Their details will be given in a future 
number. Y. 
