5 1 y RED BLOOD-CORPUSCLES. [SECT. 221. 



corpuscles, forms the serum. In certain cases, which in the human 

 subject occur especially in diseases, the coloured globules sunk 

 more or less below the surface of the fluid before coagulation takes 

 Fig- 211. place, and then the crassamentum has a 



superficial colourless or whitish stratum 

 (crusta phlogistica), which consists only of 

 coagulated fibrine and colourless blood- 

 cells, together with the fluid saturating 

 them. 



The coloured or red blood-globules, 

 also called merely blood-globules, which 



Human blond-globules, a. seen i ,-, l i ' • j.a £ 



from the surface; b. from the alone convey the red colouring matter ot 

 rendered" spherical' °V a water | the blood, are small, non-nucleated cells, 

 biood^ioMies s b iu-unt "by eV£ of the form of flattened lenses, and are 

 poratlon ' contained in the blood in such enormous 



numbers, that we cannot readily investigate their minute characters 

 without dilution, and they appear, so to speak, to constitute the 

 entire mass of the blood. Important as it might be to know the 

 proportion of the blood-globules to the plasma, and their exact 

 number and volume, yet all our investigations have been frus- 

 trated, till a short time ago, by the difficulty of the subject. 

 Even now the statements of Schmidt, according to which forty- 

 seven to fifty-four parts of moist blood-globules are contained in 

 one hundred parts of human blood, can only be designated as 

 approximative. There is only one method that is suited for the 

 attainment of this object, namely, the direct enumeration of the 

 blood-globules in accurately determined quantities of a given 

 specimen of blood ; and with this Ave need to determine as accu- 

 rately as possible, the volume of the individual blood-corpuscles 

 ( Vierordt), but hitherto the first point only has been practically 

 carried out. Vierordt, the meritorious deviser of this method, 

 counted in his own blood 5,055,000 blood-cells in 1 cub. mil- 

 limetre ; Welcker, who somewhat modified Vierordt' 's proceeding, 

 enumerated as an average, 5,000,000 in the male, 4,500,000 in 

 women. In the latter sex, however, it appears that the number is 

 still further reduced during pregnancy, and in suppression of the 

 menses. These variations may be easily understood, and the more 

 so, as Vierordt has lately shown (Arch. f. Physiol. Heilk., xiii., 

 p. 260), that in animals the number of the blood-cells varies in the 

 ratio of even one to three. 



The red blood-globules, when examined individually, present the 

 following structure : Their form is mostly that of a bi-concave or 



