CONTINUITY OF VITAL PROCESSES 31 



been supposed to be essential to life as it is found in 

 Nature to-day. But Dr. Charlton Bastian has con- 

 clusively shown that bacteria can grow and thrive 

 in solutions of ammonium carbonate which contain 

 only carbon, oxygen, hydrogen and nitrogen. These 

 four, however, are considered essential to life. Upon 

 this point all that can be said is that no form of 

 life has ever yet been found which does not contain 

 them. 



There are authorities, however, who would not 

 consider these elements strictly speaking as essential 

 to life in its widest sense. Here we have at length 

 come to really dangerous ground from a biological 

 point of view. 



And yet supposing bodies can be found that per- 

 form the processes laid down by Huxley ; but which 

 do not contain all or any of these elements, how 

 then are we to regard them ? If they integrate and 

 disintegrate and can go through the cyclic process, 

 are they on account of their chemical composition to 

 be looked upon as dead, or rather as primitive forms 

 of living matter which have long since been extinct ? 

 Would life at all times and in all places, not merely 

 on this earth of ours but in the remotest worlds, con- 

 sist essentially of carbon compounds ? This is a query 

 which of course we cannot answer without begging 

 the whole question, and assuming a knowledge of the 

 possible solutions of the problem as to the origin of 

 life, which, alas ! we do not yet possess. 



So again, how are these types which show meta- 

 bolism and a cyclic change to be distinguished from 



