126 PHYSIOLOGY OF ORGANIC LIFE. 



that although much carbonic air is expired, 

 little or nothing- is taken in ; however high the 

 authority certainly is, whence this opinion 

 has come, I, nevertheless, consider the actual 

 change of color, and of consistence, from black 

 and thick, to red and liquid, which the blood 

 undergoes as it passes from the heart through 

 the pulmonary artery, and through the lungs 

 to the pulmonary veins, is far more decisive 

 than any chemical experiments performed on 

 the air out of the body can disprove ; that in- 

 dependently of what is expelled, a considera- 

 ble quantity of matter is, nevertheless, re- 

 ceived, the quality of which it is not worth a 

 rush to ascertain ; the experiments made by 

 Mr. HUNTER, Dr. GOODWIN, &c &c. are deci- 

 sive on this point. 



Equally at variance, are physiologists, with 

 respect to the manner in which the matter acted 

 upon by the lungs is conveyed 'into the blood. 

 Instead of supposing that the parts of the air 

 which have been separated from the whole, are 

 absorbed by the extremity of the pulmonary 

 veins, as the nutritious matter which the pla- 

 centa furnishes for the support of the foetus is 

 unquestionably absorbed by the extremities of 

 the umbilical veins, or as the chyle by the 

 chylous (lacteal) vessels : it is generally sup- 

 posed that the air forces its way into the blood 

 by the most unnatural means ; not through the 



