In this the blood completes a circulation without leaving the heart ; it enters the coronary arteries near the semilunar valves, passes through a capillary network, is collected by the coronary veins, and poured into the right auricle.

By the systemic circulation the blood is carried to all parts of the body for general nourishment.

By the pulmonary circulation blood is carried to the lungs to be oxygenated and purified.

By the portal circulation absorbed nutriment is carried to the liver to be elaborated.

By the coronary circulation the heart itself is supplied.

William Harvey discovered the circulation of the blood in 1619.

Malpighii discovered the capillaries in 1661.

Fig. 19 Arteries And Veins.

I., Aorta

II., Pulmonary Artery

III., Superior Vena Cava

IV., Inferior Vena Cava

a, Innominate Artery

b, Carotid Artery

c, Subclavian Artery

d, Axillary Artery

e, Brachial Artery

f, Radial Artery

h, Ulnar Artery

i, Superficial Palmar Arch

k, Hepatic Artery

l, Renal Artery

m, Common Iliac Artery

n, Femoral Artery

o, Deep Femoral Artery

1. Innominate Vein.

2,  Internal Jugular vein

3.  Facial Vein.           

4.  External Jugular Vein

5.  Subclavian Vein.

6,  Cephalic Vein.

7,  Axillary Vein.

8,  Basilic Vein.

9.  Median Basilic Vein, 10, Median Cephalic Vein 11. Median Vein.

12, Hepatic Vein

13, Renal Vein. 14, Femoral Vein.

15, Long Saphenous Vein.

Fig. 20 a.—Aorta from Before. Fig. 20 b.—Aorta from Behind.

I to 2, Ascending aorta ; 2 to 3, arch of aorta ; 4, innominate artery ; 5, left carotid ; 6, left subclavian ; 7 to 7, intercostal and lumbar ; 8, bronchial; 9, oesophageal; 10, renal; 11. common iliac; 12, middle sacral; 13, coeliac axis; 14, gastric artery; 15, hepatic; 16, splenic 17, superior mesenteric ; 18, inferior mesenteric.