CHAP, i.] BLOOD. 27 



corpuscles in haemoglobin is even more striking than the scanti- 

 ness of the corpuscles, and is sooner affected by the administration 



vroiL 



e composition and properties of haemoglobin will be con- 

 sidered in connection with respiration. 



Of the proteid substances which form the stroma of the red 

 corpuscles this much may be said, that they appear to belong to 

 the globulin family; their exact nature need not be considered 

 here. As regards the inorganic constituents, the corpuscles are 

 distinguished by the relative abundance of the salts of potassium 

 and of phosphates. This at least is the case in man ; the relative 

 quantities of sodium and potassium in the corpuscles and serum 

 respectively appear however to vary in different animals; in some 

 the sodium salts are in excess even in the corpuscles. 



Composition of the white corpuscles. Our knowledge of the 

 exact nature of the proteid matrix of the white corpuscles is at 

 present too uncertain to enable any definite or useful statements 

 to be made, and the probable relation of the corpuscles to coagula- 

 tion has already been spoken of. The corpuscles are found to 

 contain in addition to proteid material, lecithin or protagon, gly- 

 cogen, extractives and inorganic salts, there being in the ash a 

 preponderance of potassium salts and of phosphates. The nuclei 

 contain nuclein. Upon the death of the corpuscle the glycogen 

 appears to be converted into sugar. 



Both the corpuscles and the plasma (or serum) contain gases. 

 These will be considered in connection with respiration. 



The main facts of interest then in the chemical composition of 

 the blood are as follows. The red corpuscles consist chiefly of 

 haemoglobin. The organic solids of serum consist partly of serum- 

 albumin, and partly of paroglobulin. The serum or plasma 

 contrasts in man at least, with the corpuscles, inasmuch as the 

 former contains chiefly chlorides and sodium salts while the latter 

 are richer in phosphates and potassium salts. The extractives of 

 the blood are remarkable rather for their number and variability 

 than for their abundance, the most constant and important being 

 perhaps urea, kreatin, sugar, and lactic acid. 





