352 Mr. Wilson’s Description of a 
aorta was larger than that of the pulmonary artery. It is there- 
fore necessary to recollect, that a considerable proportion of the 
blood carried to the lungs was already florid or oxygenated ; 
and also, that the lungs in this infant were larger in propor- 
tion, than in children of the same age : a smaller quantity of 
blood, therefore, was to be oxygenated, and a larger surface 
than usual was appropriated for this purpose. It appears also, 
from experiments, (such as making a person breathe air in 
which there is a greater proportion of oxygen gas than in our 
atmosphere, ) that the blood can combine with more of it than 
it does in natural respiration; it therefore is not an improbable 
supposition, that a larger quantity was combined here. A 
small drawback must be allowed, for the quantity of oxyge- 
nated blood used in the support and secretions of the lungs, 
and which is usually conveyed to them by the bronchial artery; 
but this quantity is too small to require more than this slight 
observation of it. The blood also which passed to the lungs, 
must have been again conveyed to the heart sooner, from the 
shortness of its circuit ; and must have entered the heart with 
a quicker or stronger current, than that blood which passed to, 
and was returned from, the more remote parts of the body ; 
as, in this child, the pulmonary artery and aorta were filled by 
the contraction of the same ventricle. In the hearts of other 
children, some time after birth, the muscular fibres of the right 
side are much fewer in number than in the left. 
If these circumstances are admitted as fact, viz. that the 
blood circulating through the lungs of this child was combined 
with a larger proportion of oxygen gas, and was returned in 
a quicker and stronger current into the auricle than that re- 
turned by the venae cavae, it seems reasonable to infer, that this 
