CHAPTER XVI 

 MORE ABOUT SUSPENDED ANIMATION 



I GAVE some account in the last chapter of the 

 experiments made within the last twenty years, 

 which have shown that, in certain very simple 

 organisms and in seeds, all chemical change can be stopped 

 by the application to them of methods of freezing. The 

 continuous changes which go on in these living things 

 under ordinary circumstances are arrested by the solidifica- 

 tion of what was more or less " moist " material. Water 

 in the liquid state, though it may be in extremely minute 

 quantity, is necessary for the chemical combinations and 

 decompositions, which go on in living things. Hence not 

 only the solidification of all moisture, in or having access 

 to the living bodies experimented on, arrests those 

 chemical combinations and decompositions, but very 

 thorough drying also has this result. Yet either on 

 thawing the frozen liquid or supplying moisture to the 

 " dried up " organism, the previously continuous chemical 

 and physical changes are resumed as though no arrest or 

 suspension of them had occurred. No limit is known to 

 the length of time during which this arrest may be 

 continued, and yet a resumption of living changes occur 

 when the cause of arrest — namely, either solidification by 

 cold or else dryness — is removed. The apparatus — the 

 exact structure and the exact chemical materials — of the 

 seeds or the bacteria remains uninjured and unchanged 

 by either freezing or drying carefully applied. It is, of 



