ACTION OF ARTERIAL BLOOD. 163 



composed ; otherwise, they would be incapable of ex- 

 erting any influence on the blood. 



, 75. The blood, in its normal state, possesses two 

 qualities closely related to each other, although we may 

 conceive one of them to be quite independent of the 

 other. 



The blood contains, in the form of the globules, the 

 carriers, as it were, of the oxygen which serves for the 

 production of certain tissues, as well as for the genera- 

 tion of animal heat. The globules of the blood, by 

 means of the property they possess of giving off the 

 oxygen they have taken up in the lungs, without losing 

 their peculiar character, determine generally the change 

 of matter in the body. 



The second quality of the blood, namely, the prop- 

 erty which it possesses of becoming part of an organ- 

 ized tissue, and its consequent adaptation to promote the 

 formation and the growth of organs, as well as to the 

 reproduction or supply of waste in the tissues, is owing, 

 chiefly, to the presence of dissolved fibrine and albu- 

 men. These two chief constituents, which serve for 

 nutrition and reproduction of matter, in passing through 

 the lungs are saturated with oxygen, or, at all events, 

 absorb so much from the atmosphere as entirely to lose 

 the power of extracting oxygen from the other substan- 

 ces present in the blood. 



76. We know for certain that the globules of the 

 venous blood, when they come in contact with air in the 

 lungs, change their color, and that this change of color 

 is accompanied by an absorption of oxygen ; and that 



