98 USES OF BLOOD. 



food and from the tissues, as a temporary and useless con - 

 stituent, to be excreted when opportunity offers. 



Corpuscles. The uses of the red corpuscles are probably 

 not yet fully known, but they may be inferred, at least in 

 part, from the composition and properties of their contents. 

 The affinity of haemoglobin for oxygen has been already 

 mentioned ; and the main function of the red corpuscles 

 seems to be the absorption of oxygen in the lungs by 

 means of this constituent, and its conveyance to all parts of 

 the body, especially to those tissues, the nervous and mus- 

 cular, the discharge of whose functions depends in so great 

 a degree upon a rapid and full supply of this element. 

 The readiness with which haemoglobin absorbs oxygen, and 

 delivers it up again to a reducing agent, so well shown by 

 the experiments of Prof. Stokes, admirably adapts it for 

 this purpose. How far the red corpuscles are concerned 

 in the nutrition of the tissues is quite unknown. 



The relation of the white to the red corpuscles of the 

 blood has been already considered (p. 92) ; of the functions 

 of the former, other than are concerned in this relationship, 

 nothing is positively known. Recent observations of the 

 migration of the white corpuscles from the interior of the 

 blood-vessels into the surrounding tissues (see Section, On 

 the Circulation in the Capillaries) have, however, opened 

 out a large field for investigation of their probable func- 

 tions in connection with the nutrition of the textures, 

 in which, even in health, they appear to wander. 



