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CHAPTER X. 
Plate XVII. — the heart. 
Fig. 1. A section of the human heart; a, a, the superior and in¬ 
ferior vena cava , the veins which convey the blood to the, 6, right 
auricle; and thence into, c, the corresponding ventricle; from this 
ventricle the blood is impelled through, e, the pulmonary artery , in¬ 
to the lungs; and returning by ff the pulmonary veins, it is receiv¬ 
ed into, g, the left auricle; it flows next into, h, the left ventricle; 
which by its contraction distributes the blood through the general 
arterial system:— j t the aorta , the great artery which transmits 
blood to the different parts of the body, from whence it is returned 
by veins to the caves; k, the right subclavian; Z, the right carotid 
arteries, originating from one common trunk; m, the left carotid; 
n, „the left subclavian; d, the valves of the right; t, the valves of 
the left ventricle. 
Fig. 2. The valves of the right side (tricuspid valves) separated 
from the heart; a, a, a, the carnaa column <e, or muscular fibres of 
the valves ; 6,6,6, the chorda tendinca , or tendinous filaments which 
are attached to, c, the valves. 
Fig. 3. Exhibits the artery cut open with the form of the semilu¬ 
nar valves . 
Fig. 4. A portion of the artery filled, showing how effectually 
the valves prevent the retrograde motion of the blood in the aorta 
and pulmonary artery. 
Fig. 5, 6. A section of a cutting and grinding tooth, showing 
the apertures at the root and the cavities for the vessels and nerves, 
which supply the bony part of the teeth, the enamel not being an 
organized substance. 
