210 
ON THE INTRODUCTION OF AIR INTO 
that these two circumstances ought to be taken into serious consi- 
deration ; but he believes that the quality of the air which has 
served for the respiration of man, before it is introduced into the 
veins of the animal, is very much concerned in the production of 
the phenomenon which we are now studying. It will be necessary 
to appeal to new experiments for the complete explication of this 
curious and important phenomenon. 
§ III . — The mechanism or real cause of death. 
If it is now demanded, what are the real causes of the death 
-which supervenes on the introduction of air into the bloodvessels, 
we reply, that the principal ones are, in our opinion, the following: 
1. The enormous distention of the right cavities of the heart by 
the air which is thrown into them, and which is there dilated by 
the heat of the blood — a distention which does not permit this 
organ to resume the regular discharge of its functions. 
2. The presence of air in the pulmonary artery and its ramifi- 
cations, which, mingling with the blood, gives it a viscidity, or 
spumosity , which prevents its free circulation in the pulmonary 
capillaries*. 
3. In the cases in which the air penetrates into the venous sy s- 
tem of the brain, the compression which it exercises on that organ 
may be the cause of death, without calling into the question any 
other action, physical or chemical, as yet unknown, which it may 
exercise on that organt. 
Such is, in our opinion, and after the deepest study of the symp- 
toms and changes that we have had the opportunities to observe — 
such, we say, is the mechanism of this kind of death. Nysten had 
already insisted on the distention of the right cavities, and on the 
compression of the brain in cases in which the air penetrated into 
the vessels of that organ : but he had said nothing of the third 
cause alluded to. 
It is also well understood, that when it is once disseminated 
through the whole extent of the circulatory current, the air becomes 
* It is possible also that the air contained in the pulmonary system exer- 
cises a compression on this organ, which mechanically prevents the respira- 
tion, and, if The term may he pardoned, suddenly asphyxiates ( asphixie ) the 
iung. 
t The reader must not forget how constantly we find a certain portion of 
air in the brain of horses that have been destroyed by the introduction of 
air into the jugulars, and which does not ordinarily occur in dogs, at least 
when they are placed in a horizontal position. Is this one of the reasons 
that horses are generally destroyed so much sooner than dogs by the insuf- 
flation of air ? 
