HO USE OF THE SALIVA. 



occupied by atmospherical air. A portion of intestine, 

 a stomach, or a piece of skin or membrane, acts pre- 

 cisely as the bladder, if filled with any gas. This per- 

 meability to gases is a mechanical property, common to 

 all animal tissues ; and it is found in the same degree in 

 the living as in the dead tissue. 



It is known that in cases of wounds of the lungs a 

 peculiar condition is produced, in which, by the act of 

 inspiration, not only oxygen but atmospherical air, with 

 its whole amount (|ths) of nitrogen, penetrates into 

 the cells of the lungs. This air is carried by the 

 circulation to every part of the body, so that every part 

 is inflated or puffed up with the air, as with water in 

 dropsy. This state ceases, without pain, as soon as 

 the entrance of the air through the wound is stopped. 

 There can be no doubt that the oxygen of the air, thus 

 accumulated in the cellular tissue, enters into combina- 

 tion, while its nitrogen is expired through the skin and 

 lungs. 



Moreover, it is well known that in many graminivo- 

 rous animals, when the digestive organs have been over- 

 loaded with fresh juicy vegetables, these substances 

 undergo in the stomach the same decomposition as they 

 would at the same temperature out of the body. They 

 pass into fermentation and putrefaction, whereby so 

 great a quantity of carbonic acid gas and of inflamma- 

 ble gas is generated, that these organs are enormously 

 distended, sometimes even to bursting. From the struc- 

 ture of their stomach or stomachs, these gases cannot 

 escape through the oasophagus ; but in the course of a 



