484 THE WONDER OF LIFE 



dry seed-coats of peas and beans, and of many others which 

 can germinate after prolonged desiccation, are air-proof. 

 When detached pieces were fitted on to the top of a tube 

 of mercury, above a Torricellian vacuum, no air was 

 drawn through even in months. Thus a dry seed is 

 peculiarly isolated. When the coats are wet, the absorp- 

 tion of water changes the situation, and gaseous exchange 

 begins. 



Becquerel's later experiments are very striking. He took 

 seeds of wheat, mustard, and lucerne, and perforated their 

 coats ; dried them in a vacuum at 40 C. for six months ; 

 sealed them up in an almost exhausted tube for a year ; 

 submitted them to the temperature of liquid air ( 190) 

 for three weeks, and of liquid hydrogen (250) for three 

 days ; and then put them on moist cotton wool and they 

 germinated as usual ! In a review, Prof. Cavers gives 

 a terse statement of Becquerel's conclusion. ' Bec- 

 querel finds it impossible to conceive of " life " under the 

 conditions to which these seeds were subjected, and holds 

 that life can be interrupted completely not merely slowed 

 down with no prejudice to its resumption '. 



Various fungoid organisms have been known to survive 

 twenty- two years' desiccation; various bacteria have 

 remained alive without air but with moisture for ten to 

 twenty years ; sediments containing various Protozoa 

 have shown re-vivification after five to six years. J. Noc 

 relates that some tubes with a little water and various 

 Protozoa were hermetically sealed in 1908, and were 

 recently examined. There was no trace of the Infusorians 

 which were there to start with, but there were encysted 

 Amoebae, some of which revived after ten days or so. 

 Some Protozoa dried on Tonkin commercial paper were 



