208 
PHYSIOLOGICAL PROPERTIES OF BLOOD. 
this will occur quite as readily if we use the blood of the 
same animal as of that of a different species. 
When, instead of blood charged with oxygen, we use 
blood charged with carbonic acid, death is produced according 
to the phenomena so well described by MM. Prevost and 
Dumas, and afterwards by Dieffenbach, Rayer, Bischoff, &c. 
What is the cause of death ? We think that it depends on 
the poisonous action of the carbonic acid. 
It may appear strange that violent convulsions and a very 
rapid death should be attributed to an agent which always 
exists in the blood and in a quantity not inferior to that in 
which it is found in the transfused blood. It will appear, at 
first, scarcely admissible that carbonic acid, which appeared 
so innocent in experiments performed by operators of the 
first order, can have so great a poisonous power as that 
which I have attributed to it. But it is easy to explain how 
carbonic acid has not manifested its poisonous power in the 
experiments of the observers of whom I speak. Like many 
other poisons, the quantity of this in the blood must attain 
a certain degree to manifest its poisonous effects, a degree 
which has not been reached in these experiments. In 
Roupell’s researches and in those of Lehmann, in which, on 
the contrary, this point has been passed, the poisonous 
phenomena showed themselves, and recently in those cases 
in which, among women, carbonic acid has been absorbed by 
the vaginal and uterine mucous membranes, vertigo and other 
phenomena have been produced. 
However it may be with regard to the facts which have 
already been published, here are new and direct proofs of the 
influence of carbonic acid; we remove 50 grammes of blood 
from a dog, and, after defibrinating it, we saturate it with 
carbonic acid, we then inject it into the jugular vein, towards 
the heart, of either the same animal or of another animal of 
the same species, and we see the animal die very quickly, 
after exhibiting the violent convulsive phenomena of a sudden 
and complete asphyxia. With other mammifera and birds we 
find the same thing occur. Moreover, we find that the 
death is more rapid and the convulsive phenomena all the 
more powerful, as the quantity of carbonic acid contained in 
the injected blood is more considerable 
If the injection be made very slowly, so that the animal 
shall have time to exhale by its lungs the excess of carbonic 
acid which it receives, death will not supervene. On the 
other hand, if from a certain quantity of the blood, a portion 
of which has caused the death of an animal, we remove the 
carbonic acid and replace it with oxygen, this blood no longer 
