EXTRACT XLVIII. B. 

 ON RESPIRATION, AND ATMOSPHERIC AIR. 



ATMOSPHERIC air is as essential for the maintenance of 

 life as food itself ; indeed, it may be called a food with 

 strict scientific accuracy, inasmuch as it is engaged, in all 

 metabolic processes, in carrying into the intra-structural 

 voids, by means of its oxygen, the elements of tissue 

 protoplasm, and in carrying out the elements of broken- 

 down and effete tissue elements. In this chemico-physio- 

 logical work it may be said to resemble in its modus 

 operandi the physical work performed in the economy of 

 circulation by the physical element water, and like it, it 

 is universally present throughout the areas of the globe, 

 wherever life, in all its higher forms, is functionally active. 



Vegetable and animal life take from, and add to, the 

 " sum and substance " of atmospheric air their respective 

 nutritive and refuse gaseous elements, in such manner 

 and quantity as to maintain, by the law of gaseous 

 diffusion, an equable distribution of its dual life- 

 supporting elements, and so, by a principle of reciprocity, 

 the two great kingdoms of nature co-exist, and perform 

 their respective functions, in the great laboratory of 

 nature, in biological harmony. 



Could the quantity of air taken into the respiratory 

 organism of a human being, in the course of a definite 

 period, be accurately weighed or measured, it would be 

 found to bear a proportion to the quantity of solid and 

 liquid food consumed, little, if at all, inferior materially, 

 and perhaps of as great dynamic importance, in the 

 economy of metabolism. 



