CHAPTER Vni 



THE BLOOD 



I* 





WiJi^ 



Blood is best considered as a tissue, the intercellular substance 

 of which is fluid. This fluidity of the intercellular substance allows 

 the formed elements or cells to move about freely, so that there is not 

 the same definite and fixed relation between cells and intercellular 

 substance as in other tissues. There are about 5 litres of blood in the 

 adult body, blood thus constituting about 

 one-thirteenth of the entire body weight. 



The fluid intercellular substance or 

 plasma is slightly alkahne in reaction. It 

 consists of serum albumen, globulin, 

 fibrinogen and inorganic salts, chiefly the 

 chlorid, carbonate, bicarbonate and phos- -lii?, 



phate of soda. The reaction of blood is 

 distinctly alkaline, due mainly to the 

 phosphate of soda. Its specific gravity is 

 about 1.030, while that of the whole blood 

 is about 1.060. The bulk of the plasma is 

 about equal to that of the red and the 

 white cells. 



The formed elements of the blood are: 

 (i) Red blood cefls (red blood corpuscles, 

 erythrocytes); (2) white blood cefls (color- 

 less corpuscles — leucocytes); (3) blood 

 platelets (thrombocytes); (4) blood dust 

 (haematokoniaV 



I. Red blood cells (erythrocytes) (Fig. 53, 



non-nucleated circular discs. ^ Their average diameter is about 



7.5,", their thickness 2,« at the thin centre.- A few red blood cells 



'~>f a diameter of 8/« to8.5/< (macrocytes) and about the same number 



;f red cells only about one-half the usual diameter (microcytes) 



^ Some observers describe the red blood cell as bell- or cup-shaped. (Lewis: Jour. 

 -led. Research, N. S., vol. v, 1904; Radasch: Anat. Anz. xxviii, 1906. Weidenreich: 

 .>gebn. d. Anat., 1903, 1904, 1909; Arch. f. mikr. Anat., Ixi, 1903, Ixix, 1906.) 



- As this is a quite uniform average diameter and as red blood cells are to be seen in 

 Imost every microscopic field, the diameter of the red blood cells is frequently used as 

 unit of microscopic measurement. 



107 



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Fig. 53. — Cells from Human 

 Blood. X 600. (Technic 2, 

 p. 114.) I, Red blood cell 

 seen on flat; 2, red blood cell 

 seen on edge; 3, red blood cells 

 forming rouleaux; 4, 4, small 

 and large lymphocytes; 5, 

 mononuclear leucocj'te; 6, 

 transitional leucocyte; 7, 

 poh'morphonuclear leucocyte, 

 containing neutrophile gran- 

 ules; 8, poly nuclear leucocyte, 

 containing eosinophile gran- 

 ules; 9, mononuclear leuco- 

 cyte, containing basophile 

 granules. 



I, 2, 3) are in man 



