THE HEART AND VASCULAR SYSTEM. 175 



organs from V 3000 to V 2000 inch in diameter, but all permit the 

 passage of blood-corpuscles. Their form is dependent on the 

 form of tissue supplied. 



COMPOSITION OF THE BLOOD. Blood within the vessels is a 

 perfect fluid, of alkaline reaction, saline taste, average specific 

 gravity 1055, and feeble, peculiar odor. Within the arterial 

 vessels it is bright-red color, becoming in the veins (particularly 

 the venaa portaa and pulmonary arteries) a deep maroon or red- 

 dish-black color. 



It constitutes about one-twelfth or one-fourteenth of the 

 body-weight, and consists of the liquor sanguinis and the cor- 

 puscles, red, white, etc. 



The red corpuscles are elastic, of specific gravity 1088, non- 

 nucleated, and average about one three-thousandth line in diam- 

 eter. A cubic millimetre of blood contains, in the male, 5,000,- 

 000 red blood-cells, and, in the female, 4,500,000. On evapora- 

 tion they become stellate, and swell up with water. They vary 

 much in size and shape in different animals, and contain haemo- 

 globin, which carries oxygen to the tissues and C0 2 to the lungs. 



The colorless or white blood-corpuscles are free nucleated 

 protoplasmic masses, capable of amoeboid movement. They con- 

 tain fat-corpuscles, myosin, cholesterin, protagon, glycogen, and 

 nuclein. There is about 1 white corpuscle to every 500 red cor- 

 puscles, or in 1 cubic millimetre of blood there are present about 

 from 8,000 to 10,000 white corpuscles. 



The liquor sanguinis is a pale, amber-colored fluid, holding 

 the corpuscles in suspension, and very prone to coagulate. The 

 coagulation of the blood results in the formation of a clot, or 

 crassamentum, and the serum, in the following manner : 



r Corpuscles, j 

 Fluid blood ...... J Plasma or S Fibrin 



I Sangufnis. /Serum. Serum. 



The composition of the blood is about as follows : 



( Wntor 90f , 



Corpuscles, 328.. { 22^' ''HM Hemoglobin, 



8 L Other organic compounds. 



Fibrin, 

 Albumen, 



Other organic compounds, 

 Sodium and potassium salts, 

 Calcium and mugm-sinni salts. 



1000 



