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 many of the lower forms 
of life arose spontaneously from dead matter, as maggots in cheese 
or pond-scum on a stagnant pool. What gave rise to the belief that 
bacteria were spontaneously generated was ‘that sometimes 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, when 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- 
