INTO THE VEINS OF LIVING ANIMALS. 
317 
bubbles of air either in the left cavities, or in the veins or arte¬ 
ries of some of the limbs, a circumstance which did not exist in 
the dogs opened immediately after the experiment. 
We must conclude from this, that, after a certain time, the 
air contained in the right cavities, and the pulmonary artery, is 
forced into the pulmonary veins, and thence carried into the left 
cavities, and the arterial and venous systems generally. 
Horses. —In these animals, as well as in the dog, when 
opened immediately after the accidental introduction of air into 
the jugular vein, the right cavities of the heart are always found 
distended with air, either free or mixed with the blood which 
they contain. But beside this, there is almost always found air 
in the left cavities, in the aorta, and always in the vessels of 
the brain; while among the dogs there was only one case out 
of fifteen in which any air was found in these parts. 
What is the cause of this remarkable difference between the 
two animals. If we dared to hazard an explanation, we should 
say, that the ultimate ramifications of the pulmonary vessels, 
being larger in the horse than in the dog, the air mixed with 
the blood traverses them more readily, and that, consequently, 
we may expect to find it in the left cavities, and, therefore, in 
the aorta, at a time when it cannot have forced its way into 
the same parts in the dog. When, however, the dogs are not 
opened until some days after the introduction of the air into the 
jugular, it may be found in the left cavities of the heart, the 
aorta, and in the arteries which spring from it, and also in the 
veins which accompany them. 
III. Accidents resulting from, or effects of the introduction of air 
into the sanguineous system in animals—the causes of these 
accidents^ and of the loss of life which may he the result. 
When we assisted at the first experiments made by M. 
Amussat we were pre-occupied with the idea of the sudden, in¬ 
stantaneous deaths which, according to certain physiologists, 
would be produced by the introduction of a small quantity of air 
into a vein near the heart, in the performance of certain surgical 
operations: what then was our surprise,—I had almost said our 
disappointment,—when we saw the greater part of the dogs that 
were the subjects of our experiments thus inhaling the air by 
long draughts, and for many successive minutes, and not only 
without death resulting, but without their seeming to feel any 
very serious inconvenience! 
There are, however, certain symptoms which generally follow 
the introduction of atmospheric air into the veins. At the expi¬ 
ration of a short time—from one to ten minutes—the respiration 
VOL. XI. u u 
