280 ANIMAL STUDIES 



. ' heart ceases to beat, other organs of the body are alive 

 wji^ithat is, are able to perform their special functions. The 

 ^muscles can contract for minutes or hours (for a short time 

 in warm-blooded, for a long time in cold-blooded animals) 

 after the animal ceases to breathe and its heart to beat. 

 Even longer live certain cells of the body, epecially the 

 amoeboid white blood-corpuscles. These cells, very like 

 the Amoeba in character, live for days after the animal is, 

 as we say, dead. The cells which line the tracheal tube 

 leading to the lungs bear cilia or fine hairs which they 

 wave back and forth. They continue this movement for 

 days after the heart has ceased beating. Among cold- 

 blooded animals, like snakes and turtles, complete cessa- 

 tion of life functions comes very slowly, even after the 

 body has been literally cut to pieces. 



Thus it is essential in defining death to speak of a 

 complete and permanent cessation of the performance of 

 the life processes. 



