84 The Science of Life. 



no material element in the organism which is not to be 

 found in the inanimate environment. It is all a ques- 

 tion of chemical composition. The results of synthetic 

 chemistry have broken down the supposed barrier 

 between the organic and the inorganic. 



Nor can any foothold be found in emphasizing the 

 co-existence of psychical phenomena and life, for it is 

 plain that we know, to say the most, very little as to 

 psychical phenomena in the simplest animals, and 

 nothing as to their expression in plants. 



The difficulty of defining vitality remains when we 

 contrast not the bird and the pebble, but the living bird 

 The Quick anc * tke cor P se > ^ e quick and the dead. 

 and the Even in practice it is often difficult to tell 



Dead - whether an organism is alive or dead; the 

 theoretical distinction is not less difficult. The contrast 

 is indeed great between the soaring lark and the dead 

 bird at our feet ; but what if we contrast the corpse with 

 the entranced fakir, or with the dried-up bear-animal- 

 cule, or rotifer, or paste-eel, or even more familiarly 

 with the seed many years old? 



As far back as 1719, Leeuwenhoek wrote to the 

 Royal Society of London an account of the revivifica- 

 tion of the little bear-animalcules or Tardigrada, animals 

 distantly related to mites, which occur for instance in 

 the gutters of house -roofs and have extraordinary 

 powers of surviving drought. The same is true of 

 many small Crustacea and of some rotifers or wheel- 

 animalcules, and is perhaps most securely known in 

 regard to the minute thread-worms (AnguillulidaB) known 

 as paste-eels and vinegar-eels, which may "come to life 

 again " after being dried up for fourteen years. It is 

 less surprising that the same should be true of many 

 eggs and spores and unicellular organisms, where the 

 structure is much simpler. 



Now it is plain that these organisms in a state of 

 latent life, as Claude Bernard phrased it, or ' ' potential 

 life", as Preyer calls it, are not dead, since they may 

 live; yet beyond this potentiality it is difficult to say 

 what characteristic of livingness they possess. 



Of interest in the same connection are the phenomena 



