50 



HUMAN PHYSIOLOGY 



compassing walls save at a few places. For the most 

 part the surfaces of the organs bear upon surfaces of 

 the body walls but do not adhere to them. The arrange- 

 ment permits a certain amount of gliding of one upon 

 the other. There cannot normally be a separation be- 



FIG. 5. Suggesting the thoracic and abdominal cavities parted by 

 the diaphragm. The abdominal viscera are drawn upward, creating 

 a space above the bladder where none normally exists. 



tween them -since this would involve the creation of a 

 vacuum. The relation between an organ and the 

 opposing body wall is much like that between two 

 plates of glass which have been moistened and laid 

 together. One will slide freely upon the other, but it 



