710 



RED CORPUSCLES OF BLOOD. 



Red Corpuscles of Frog's Blood : — a a, their 

 flattened face ; b, particle turned nearly edge- 

 ways ; c, Colourless corpuscle ; d, red corpuscles 

 altered by dilute acetic acid. 



granules ; this is most distinctly brought into view by treating 

 the blood-disks with Acetic acid, which renders the remaining 



portion extremely 

 Fig. 370. transparent, while 



it increases the 

 opacity of the nu- 

 cleus (Fig. 370, d). 

 It is remarkable, 

 however, that the 

 Red corpuscles 

 of the blood of 

 Mammals should 

 possess no obvious 

 nucleus ; the dark 

 spot which is seen 

 in their centre 

 (Fig. 371, 6) being 

 merely an effect 

 of refraction, con- 

 sequent upon the 

 double-concave form of the disk. When the Corpuscles are treated 

 with water, so that their form becomes first flat, and then double- 

 convex, the dark spot 

 Fig. 371. disappears ; whilst, on 



the other hand, it is 

 made more evident 

 when the concavity is 

 increased by the par- 

 tial shrinkage of 

 the corpuscles, which 

 may be brought about 

 by treating them 

 with fluids of greater 

 density than their own 

 contents. The size of 

 the Red Corpuscles is 

 not altogether uniform 

 in the same blood ; 

 thus it varies in that 

 of Man from about - 

 the I -4000th to the l-2S00th of an inch. But we generally find 

 that there is an average size, which is pretty constantly maintained 

 among the different individuals of the same species ; that of Man 

 may be stated at about l-3200th of an inch. The following Table* 

 exhibits the average dimensions of some of the most interesting 

 examples of the Red blood-corpuscles in the four classes of Verte- 



• These measurements are chiefly selected from those given by Mr. 

 Gulliver in his edition of Hewson's Works, p. 236, et seq. 



Red Corpuscles of Human Blood; repre- 

 sented at a, as they are seen when rather 

 within the focus of the microscope, and at b, 

 as they appear when precisely in the focus. 



