EXTRACT XLVIII. A. 



ON RESPIRATION, PULMONARY AND CEPHALIC. 



RESPIRATION is, or may be regarded as, a process of 

 chemico-physiological admixture of atmospheric air with 

 the blood, as it passes in minutely subdivided processional 

 order through the lumina of the pulmonary capillaries, 

 under the guidance of a systemico-sympathetically regu- 

 lated nervine machinery at a measured rate, according to 

 the existing bodily physiological conditions and necessities. 

 In the immediate process of chemico-physiological admix- 

 ture of air and blood, in the delicate vesicular substance 

 of the ultimate pulmonary textures, an interchange of 

 chemical elements is effected, the immediate outcome of 

 which is the disengagement or discharge of superabundant 

 carbon and the engagement or substitution of subabundant 

 oxygen, which latter becomes the predominant chemical 

 instrument of metabolic change in the prolonged and 

 complex processes of nutrition and elimination, which 

 make up in great part the chemico-physical phenomena 

 of life. It therefore becomes self-evident that a physio- 

 logically perfect performance of this function is essential 

 to the production and maintenance of health, any deviation 

 from which must necessarily be followed by a proportionate 

 alteration of its tone and condition. The chemistry of 

 the process of interchange of gases arising from the 

 contact, or admixture, of the atmospheric air with the 

 blood, in the process of respiration, has not yet been 

 fully mastered ; we must, therefore, confine ourselves to 

 treating of only a few of its most salient points, as, for 

 instance, how the two principal physical constituents of 



