101 
AN EXPERIMENTAL INQUIRY INTO THE NATURE OE THE 
METAMORPHOSIS OF SACCHARINE MATTER, AS A NOR- 
MAL PROCESS OF THE ANIMAL ECONOMY. 
By Dr. Pavy. 
The author begins b} r observing, that the saccharine 
matter met with in the animal economy is derived from two 
sources — from the vegetable kingdom, and from the liver of 
the animal itself; in each case being poured into the general 
circulation through the hepatic veins. The liver not only 
enjoys the power of forming sugar, but it likewise exerts (as 
shown by the experiments of Bernard) some modifying influ- 
ence over that which is traversing its capillaries, and: which 
has been absorbed from the food, by which it is transformed 
from vegetable into animal sugar, and thus rendered more apt 
for serving in the processes of animal life. 
The sugar poured into the general circulation through the 
hepatic veins is conveyed to the capillaries of the lungs, 
where it in great part disappears, but never entirely so, 
according to very numerous analyses which the author has 
made on this subject. If the blood be traced onwards from 
the arteries through the systemic capillaries into the veins, 
the small amount of sugar which impregnates arterial blood 
will be found to be still undergoing a process of destruction ; 
and what appears exceedingly interesting, this process of 
destruction is not carried on with equal activity in the dif- 
ferent parts of the system at large. In the capillaries of the 
chylo-poietic viscera, the destruction is so complete, that the 
blood in the portal vein may be entirely free from saccharine 
principle, when the blood returning from other parts, as that 
contained in the femoral or jugular veins, remains slightly 
impregnated. This curious fact has a bearing that will be 
presently adverted to, with reference to the views to be 
advanced concerning the nature of the metamorphosis of 
sugar in the animal economy. 
The principal seat of destruction of saccharine matter in the 
animal system being located in the respiratory organs, seems 
at first sight to support the theory of Liebig — that sugar is 
one of those substances which undergoes a process of com- 
bustion, by its direct combination with oxygen and its reso- 
lution into water and carbonic acid. Some experiments on 
the temporary obstruction of the respiration, and the exami- 
nation of arterial blood before and after the operation, led 
the author to call in question this view, as he observed that 
