INTO THE VEINS OF LIVING ANIMALS. 
315 
the brute, as applicable to the introduction of air into the veins 
of the human being during certain chirurgical operations. 
L The mechanism of the accidental introduction of air into the 
veins, and the pathognomonic symptoms of that introduction. 
When the inferior portion of one of the jugular veins is opened, 
and the incision is sufficiently large, or when these veins are laid 
bare, a flux and reflux of the blood is visible, isochronous, with 
the inspiration and expiration of the animal. If the vein is 
opened, a certain quantity of atmospheric air insinuates itself at 
the incision, and penetrates into the right cavities of the heart. 
The indication, and, in some sort, the j)athognomonic one, of 
this introduction of the air, consists in a peculiar sound, which, 
in the dog, resembles that made in the act of lapping, and in the 
horse has more of a gurgling (glouglou) or gargling character. 
The principal cause of the introduction of air into the jugular 
vein thus opened is the act of inspiration, for the lapping or 
gurgling noise is synchronous wdth it—becomes accelerated with 
it—and grows louder and louder in proportion as the breathing is 
hurried or laborious. Such is the principal cause of the introduc¬ 
tion of the air, but it is not the only one; in fact, the gurgling 
noise is sometimes louder and more precipitate than the inspira¬ 
tory action, and then it becomes synchronous with the beating of 
the heart; but, in this case, the diastole of the right cavities 
(of the right ventricle more especially) concur with the dilatation 
of the chest, in causing the introduction of air into the circu¬ 
latory system. Undoubtedly, the first of these causes is more 
powerful than the other, but that is no reason why we should 
altogether neglect the least effective cause. 
This lapping or gurgling noise, at the opening into the jugular 
vein, is an infallible proof of the introduction of air into the cir¬ 
culatory system. There is, however, another physical proof of this; 
there is a bellows sound, with or without gurgling, which is soon 
heard in the region of the heart, and which takes place in the 
right cavities of that organ. It continues for a long time after 
the introduction of the air has ceased to operate ; it is syn¬ 
chronous with the movements of the heart, and not with those of 
inspiration and expiration. 
Many physiologists, and among them Ur. Poiscuille, have 
clearly demonstrated the influence of the act of inspiration 
on the motion of the blood in the veins in the neighbour¬ 
hood of the heart, and, consequently, on the introduction 
of the air into these veins when they communicate with the 
atmosphere by means of an opening in a situation where 
the dilatation of the thorax exercises its peculiar influence 
