66 PHYSIOLOGICAL CHEMISTRY. 



II. The Form-elements of the Blood. 

 The Bed Blood-corpuscles. 



The blood-corpuscles are round, biconcave disks without mem- 

 brane and nucleus in man and mammalia (with the exception of 

 the llama, the camel, and their congeners). In the latter animals, 

 as also in birds, amphibia, and fishes (with the exception of 

 the cyclostoma), the corpuscles have in general a nucleus, are 

 biconvex and more or less elliptical. The size varies in differ- 

 ent animals. In man they have an average diameter of 7 

 to 8 /* (n = 0.001 m.m.) and a maximum thickness of 1.9 //. 

 Their specific gravity is 1.088 to 1.089 (C. SCHMIDT) or 1.105 

 (WELCKER). They are heavier than the blood-plasma or serum, 

 and therefore sink in these liquids. In the discharged blood they 

 may lie sometimes with their flat surfaces together, forming a 

 cylinder like a roll of coin. The reason for this is unknown, but 

 as it may be observed in defibrinated blood it seems probable that 

 the formation of fibrin has nothing to do with it. Seen with the 

 microscope, each blood-corpuscle has a pale yellow color, and only 

 in moderately thick layers is the color somewhat reddish. 



The number of red blood-corpuscles is different in the blood of 

 various animals. In the blood of man there are generally 5 million 

 red corpuscles in 1 c.mm., and in woman 4 to 4.5 million. 



On diluting the blood with water and alternately freezing and 

 thawing it, as also on shaking it with ether, or by the action of 

 chloroform or bile, a remarkable change takes place. The blood- 

 coloring matters, which are hardly free in the blood-corpuscles, but 

 rather, according to the view of HOPPE-SEYLEE, are combined 

 with some other substance, perhaps lecithin, are by this means 

 set free from these combinations and pass into solution, while 

 the remainder of each blood-corpuscle forms a swollen mass. 

 By the action of carbon dioxide, by the careful addition of acids, 

 acid salts, tincture of iodine, or certain other bodies, this residue, 

 rich in albumin, condenses and in many cases the form of the 

 blood-corpuscles may be again obtained. This residue has been 

 called the stroma of the red blood-corpuscles. 



