THE NUMBER OF CORPUSCLES. 



149 



collective volume can be directly read off. 1 The estimation can be made 

 with a small quantity of blood, and is therefore capable of being used for 

 clinical purposes. The average percentage of corpuscles in human 

 blood, as obtained by 

 these several methods, 

 is about 48, or very 

 nearly one-half of the 

 entire amount of blood. 

 In the horse it is 53 

 per cent., in the pig 

 43'5 per cent., in the 

 dog 35'7 per cent., 

 and in the ox 32 per 

 cent. Hedin obtained 

 in himself an average 

 percentage total cor- 

 puscular volume of 51, 

 the greatest differences 

 in his own blood being 

 54-4 and 48 per cent. ; 

 but the average for a 

 large number of adult 

 males was 48 and of 

 females 4 3 '3. In chil- 

 dren of 6 to 13 years 

 the amount was 45 per 

 cent. 



Number of corpus- 

 cles. The number of 

 red corpuscles in a 

 cubic millimetre of 

 blood was determined 

 by Vierordt and Wel- 

 cker to be about 

 5,000,000 in adult 

 men. There are rather 

 fewer in women (about 

 4,500,000). Vierordt's 

 method consisted in 

 diluting the blood with 

 a known amount of 

 fluid which would pre- 

 serve the corpuscles, 

 and counting the number in a measured amount of the mixture. The same 

 method is still in use, but its application has been greatly simplified in the 



1 An indirect method, based on the principle of centrifugalising blood with varying 

 amounts of salt solution, and determining the organic nitrogen in the supernatant fluid, has 

 been introduced by M. andL. Bleibtreu (Arch. f. d. ges. Physiol., Bonn, 1891, Bd. li. S. 151), 

 who claim to be able to estimate by its aid, not only the total corpuscular volume, but even 

 the average volume and weight of a single blood corpuscle. The method has, however, 

 been sharply criticised. (Hamburger, Centralbl. f. Physiol., Leipzig, 1893, Bd. vii. S. 161; 

 and Virchows Archiv, 1895, Bd. cxli. S. 230 ; Eyckmann, Arch. f. d. ges. Physiol., Bonn, 

 1895, Bd. Ix. S. 340 ; and Hedin, ibid., S. 360). See further, on the same subject, Lange, 

 ibid. t 1892, Bd. lii. S. 427, and Bleibtreu, ibid. t Bd. Ix. S. 405. 



SO) 



FIG. 21. Oliver's apparatus for estimating the number of 

 blood corpuscles, a, measuring pipette ; b, dropper to 

 contain Hayem's fluid ; c, mixing tube graduated in 

 percentages ; d, mode of making the observation. (This 

 must be done in a dark room. ) a, b, and c are natural size. 



