THE CKLL. 33 



is a veiy important property because it is the means through 

 wliich the nature of environments is recognized. Many of the ac- 

 tivities of the body are responses to impulses resulting from stim- 

 ulation of irritable cells. Irritabilit}^ is the property of cells which 

 enables an animal to communicate with its environments as, 

 sight hearing, smell, etc. Irritability may be intensified or 

 diminished by pathological processes. Thus chemic variations, 

 resulting from katalKilism in tissues affected with inflammation, 

 produce increased irritability or intensify stimulation of nerves, 

 and is manifested by hyperasthesia or by pain. iVncmic and 

 \ enous hyperemic tissues are usuallv less sensitive than normal 

 tissues because of the accumulation of waste product that tend 

 t(T inhibit impulses or diminish irrital^ility. Correlation of the 

 cell to the entire organ is of considerable moment, and is de- 

 pendent upon irritability and response to stimuli. 



