206 



BLOOD 



to contain a very delicate stroma (spongioplasm) and fluid matrix (hyal- 

 oplasm, with hemoglobin). The red corpuscles have a tendency when ex- 

 posed, as in a drop mounted under a cover-slip, to arrange themselves in 

 rows, like coins in a pile, concave surfaces apposed, forming rouleaux. 

 Drop preparations show after a short time also an increasing number of 

 plastids with puckered or spiny surfaces, crenated corpuscles. This condi- 

 tion results from evaporation producing a medium of greater density than 



that of the normal blood plasma. Any me- 

 dium of density equal to that of the plasma 

 of any particular blood is spoken of as an 

 isotonic solution for that blood. The solu- 

 tion in most common use for human blood 

 is a 0.9 per cent, solution of sodium chlorid 

 in distilled water. Solutions of higher den- 

 sity are hypertonic; these produce exosmotic 

 currents causing destruction leading through 

 crenation. Solutions of lower density, for 

 example, water, are Injpotonic; they produce 

 destruction (hemolysis) through endosmosis 

 causing swelling, a stage of which shows a 

 saucer-shaped corpuscle. This is accom- 

 panied by laking, or extraction of hemoglo- 

 bin, giving rise to A ^ 

 Mood shadows; and 

 final bursting, leav- 

 ing a debris called FIG. 

 hemokonia. 



The number of 

 red corpuscles in 

 the blood is subject file; 

 to constant varia- 

 tioii between wide 

 limits. Many 

 physiologic condi- 

 tions influence their total number, as well as the relative proportion of 

 red elements to the white. The average number of red corpuscles in the 

 adult male is about 5,000,000 per cubic millimeter. In young robust 

 persons the number may be considerably higher. The number may also 

 be much reduced by considerable hemorrhages or by the imbibition 

 of large quantities of fluid. Profuse perspiration tends to produce 



FIG. 219. BLOOD CELLS 

 FROM A SPECIMEN OF 

 FRESHLY DRAWN UN- 

 STAINED HUMAN BLOOD. 



A, red blood corpuscles, 

 deep focus, showing a light 

 center and dim margin; B, 

 the same with a higher focus; 

 the center, being slightly out 

 of focus, is dim while the 

 margin is light; C, crenated 

 red corpuscles from the mar- 

 gin of the preparation; a, 

 deep focus; 6, higher focus; 

 D, two polymorphonuclear 

 leukocytes; E, large mono- 

 nuclear leukocyte. X 750. 



o 



220. SHOWING THE 

 ACTION OF WATER UPON 

 THE RED BLOOD COR- 

 PUSCLE. 



a, the corpuscle in pro- 

 b-e, various stages in 

 transformation which 



leaves only a 'shadow' e; 



diagrammatic. (After 



Schafer.) 



