SYSTEMATIC SYNTHESIS OF TISSUES INTO ORGANS. 321 



FlQ. 210. 



Back view of Heart. 



908. THE HUMAN- 

 HEART is merely a hol- 

 low, heart-shaped mus- 

 cle, with several com- 

 partments and valves, 

 lined with a continua- 

 tion of the lining of 

 the veins (the serous 

 coat), and covered with 

 a similar coat; three 

 coats in all. It weighs 

 about ten ounces, is 

 about five inches in 

 length by three and a 

 half in diameter, and is 



enclosed in a heart-case (pericardium), the inner surface 

 of which is a continuation of the membrane forming the 

 surface of the heart. 



909. THE HEART is SUSPENDED to the spinal column 

 in the upper part of the chest by the blood-vessels and 

 ligaments connected with its base (that is above), and 

 extends downward, forward, and slightly to the left, be- 

 hind the breast-bone ; the place where it is felt beating 

 being against its extreme left and lower point. 



910. WHEN THE HEART CONTRACTS, its point is 

 thrown forward and strikes against the chest-walls ; this 

 point being supposed to be over the centre of the heart, 

 it is thought to be lower and more to the left than it is. 



911. Illus. Speakers will, unawares, not unfrequently indicate 

 their true feelings by referring to the heart, and placing the hand more 

 nearly over the stomach than over the region the heart occupies. 



912. Remark. Instances have occurred in which the heart inclined 

 to the right rather than the left side. 



913. THE HEART is SEPARATED FROM THE LUNGS, 

 between which it hangs, by its heart-case, and by the 

 partitions 17, Fig. 211, that pass across from the breast- 



908. What is ? 909. How is ? 910. Effect when ? 911. What is a fre- 

 quent blunder of speakers ? 913. How is ? 

 14* 



