AND ANIMAL LIFE. 



of those materials essential to support the gra- 

 dual loss of the constitution ; its office is to 

 act on the principles contained in the sanguineous 

 fluid, and if these be deficient the usual chemical 

 changes will also be affected. 



CCCCLXVII. It is from the above causes 

 that debility follows excessive exercise ; and when 

 that condition of the system becomes oppressive 

 the regularity of the respiration is disturbed; and 

 this alteration also tends to augment the general 

 weakness, and to deteriorate still more the proper- 

 ties of the blood. 



CCCCLXVI1I. In regarding oxygen as one of 

 the principal agents of the universe, through 

 whose energetic influence the animal and vege- 

 table creation are enabled to display their various 

 endowments, 1 do not by any means imagine 

 that the grand effects of its power are referrible 

 to its simple diffusion or presence, but rather to 

 its innumerable combinations with whatever is requir- 

 ed for the ultimate ends of these si/stems of Nature 

 Whether we regard the secretions of the kid- 

 neys, mucous membranes, or the liver, or whe- 

 ther we examine the qualities of the blood or 

 constitution of the solids, we observe every where 

 acids, alkalies, and a variety of other combina- 

 tions. In many chemical substances without the 

 body these are, in many instances, inert or active 

 acording to the quantity of oxygen which they 

 contain. It must be allowed, that chemical 



