PHYSIOLOGICAL PROPERTIES OF LOOD. 207 
at this result* and he found no other cause than “ the differ¬ 
ence between arterial and venous blood.” 
I find that venous and arterial blood only differ from each 
other with respect to the quantities of oxygen and carbonic 
acid which they contain: both will kill if charged with car¬ 
bonic acid ; neither will produce any disturbance if charged 
with oxygen. Numerous experiments have led me to the 
following results:— 
1. The blood of any vertebrate animal, whether arterial or 
venous, proceeding from an animal of any of the four classes, 
and charged with oxygen until it is of a rusty red, may be 
injected without danger into the veins of any vertebrate 
animal, provided that the quantity be not too considerable. 
2. The blood of any vertebrate animal, whether arterial or 
venous, sufficiently charged with carbonic acid to be blackish, 
cannot be injected into the veins of any warm-blooded animal 
(mammal or bird) without producing phenomena of asphyxia 
and generally death, after violent convulsions, provided that 
the quantity of blood be not less than a five hundredth of 
the weight of the animal, and provided also that the injection 
be not made too slowly. 
I have injected into the jugular vein of dogs, the blood of 
rabbits, guinea-pigs, cats, cocks, hens, pigeons, ducks, tor¬ 
toises (three species), frogs, and eels. When I used fresh 
arterial blood, or venous-blood defibrinated and charged with 
oxygen, I have never observed anything but a momentary 
alteration of the respiration and of the circulation, which 
always follows transfusion by the jugular vein, even when 
using the blood of the same animal, an alteration which 
depends, doubtless, principally on a distension of the right 
auricle by the blood injected. I have injected from 20 to 40 
grammes of different blood into a dog without producing 
any great effect upon its health. In other experiments, in 
which, before the transfusion, I have taken as much blood 
from the dog as I intended injecting, I have introduced with 
impunity into the circulatory system as much as 100, and 
on one occasion, 150 grammes of a bird’s blood. I have 
likewise transfused, without injury, the blood of hens and 
pigeons into rabbits. On the other hand, with hens, cocks, 
and pigeons, after taking from them from 10 to 20 grammes 
of blood, I have, with impunity, transferred a similar quan¬ 
tity of the blood of dogs, guinea-pigs, or rabbits. 
During these experiments, especially when operating on 
birds, there may arise difficulties of the respiration and cir¬ 
culation, and even death may suddenly supervene, when we 
inject the blood too quickly, or in too large a quantity ; but 
