THE INORGANIC REALM 565 



But this is precisely what seems not to happen with living proto- 

 plasts. No two living things are ever expected to act in the same 

 way in all respects. Furthermore, the theory of evolution as we 

 have seen, assumes that the halves of a cell divided by fission have 

 individual differences such as we should have no reason to expect 

 in the artificial protoplasts of a single batch. We may well believe 

 that something quite essential to life will always elude the efforts 

 of any man to create a living thing. Nothing that has been done 

 gives any assurance of the possibility of realizing such a dream. 



It used to be supposed that the transformation of a lifeless into a 

 living thing might be scientifically demonstrated to occur in the 

 appearance of bacteria in a putrescible substance. The supposed 

 transformation was called spontaneous generation, a term also ap- 

 plied to an older notion widely held that manj^ of the lower forms 

 of life arose spontaneouslj- from dead matter, as maggots in cheese 

 or pond-scum on a stagnant pool. What gave rise to the belief that 

 bacteria were spontaneouslj^ generated was that sometmies after 

 a broth had been boiled in a flask and all air excluded, bacteria 

 did appear within a few days. Investigation showed, however, 

 that in these cases spores were present which were able to resist 

 an amount of heat fatal to the plants in their actively dividing 

 condition; and one had only to repeat the boiling till all the plants 

 were killed in order to obtain a broth which could be kept indef- 

 initely. Science was thus left without any proof of spontaneous 

 generation, and it must now be said that so far as we know every 

 organism has had a living parent or parents. The aphorism "All 

 life comes from former life " still remains undisproved. 



Those who doubt that there is any essential difference be- 

 tween living and lifeless things may still urge in favor of 

 their view that certain plants are to all appearance practically 

 lifeless during their so-called resting period; and if that be 

 true we have a lifeless thing coming to life simply as a con- 

 sequence of a change in temperature. So also, many simple 

 organisms when frozen lose all trace of life except that they 

 live as before, w^ien they are thawed out. They may be 

 submitted to a temperature of 250° below zero centigrade 

 for any length of time and will resume their activities when 

 warm. Or, they may be dried so as to show no more sign of 

 life than so much inorganic dust, and then be revived by 

 moisture. Thus when there is too much or too little heat, 

 or not enough water present to permit signs of life, an or- 

 ganism may be as inactive as a crystal and indistinguishable 

 from a lifeless thing except in so far as under favorable condi- 



