SUSPENDED ANIMATION 177 



and adds his own blunders to those of the original 

 reporter. 



The action of extreme cold in arresting life in such 

 minute organisms as plant seeds and bacteria without 

 destroying the possibility of the resumption of those 

 chemical and physical changes when warmth is restored, 

 is dependent on the fact that those chemical changes 

 can only proceed in and by the aid of liquid water. 

 When thoroughly frozen the chemical constituents of 

 minute organisms and seeds — which until frozen were 

 living and undergoing continuous, though perhaps slow, 

 change — become solid, and can no longer act on one 

 another or be acted on by surrounding chemical bodies 

 equally reduced in temperature. They may be compared 

 to the solid dry constituents of a Seidlitz powder — one 

 an acid, the other a carbonate. So long as they are 

 dry they remain — when mixed and shaken together — 

 inert, without action on one another. Even if one is 

 dissolved in water and then frozen solid and mixed in 

 a powdered state with the other at an equally low 

 temperature the mixture remains dry and inert. Nothing 

 happens so long as the low temperature is maintained. 

 But if we raise the temperature above the freezing-point 

 — so as to liquefy the solution — chemical action will 

 immediately ensue. With much fizzing and escape of 

 gas the two chemicals will unite. The effect of cold on 

 living matter is of this nature. It is a real " suspension " 

 of the changes which were — however slowly and quietly — 

 going on before complete solidification of the protoplasm 

 by freezing. A frozen seed and frozen bacteria are in 

 a state of " suspended animation." 



It is not the fact that absolutely all chemical union 



and change whatsoever is prevented — that is to say, 



arrested or suspended — by extreme cold, although the 



union with oxygen and other such changes of the essential 



12 



