INTERNAL ORGANS. 



termed the diaphragm or midrifF; the anterior 

 part is named the thgrax or chest: and the 

 posterior the abdomen or beily. The thorax 

 contains t\\e lungs and heart ; the abdomen the 

 stomachy intestines ^ liver, spleen or mik, pan^ 

 creas or sweetbread, kidneys, and bladder. 



Of the Lungs. 



In describing the lungs, it is necessary ttj 

 begin with the trachea or windpipe, which is 

 a cyhndrical cartilaginous tube, extending from 

 the throat to the chest. The trachea is not 

 made up of one entire cartilage, but of several 

 cartilaginous rings, which are united by strongr 

 membranes ; and such is the elasticity of these 

 cartilages, that the tube is enabled to preserve 

 its cylindrical form, even when it receives con- 

 siderable pressure, and thereby affords free in- 

 gress and egress to the air in respiration. The 

 membranes also are elastic, so that the wind- 

 pipe may be either elongated, shortened, 

 or bent, in some degree. The upper part 

 of the trachea is composed of stronger 

 cartilages than the other parts of the tube, 

 and is termed larynx ; to this is connected ^ 



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