18 LIFE: ITS ORIGIN AND NATURE 
the origin of all other living matter; and it 
may be said that this problem remains today 
unsolved, and remains one of the most baffling 
problems of modern science. Once life has be¬ 
gun, its gradual evolution into more and more 
complex and highly developed forms is conceiv¬ 
able, but the question of its ultimate origin re¬ 
mains today still shrouded in mystery. 
THE EVOLUTION OF LIFE 
Ever since the time of Charles Darwin, the 
concept of evolution has been more or less a 
commonplace in the minds of thinking men. 
We know that higher forms of life have grad¬ 
ually evolved from more lowly and simpler 
forms. The fact of evolution, however, does 
not necessitate any particular theory as to how 
evolution ivories. The particular theory of ev¬ 
olution propounded by Darwin has now been 
supplemented or changed by newer researches, 
but the causes of evolution are to a great ex¬ 
tent as mysterious as ever. Lamarck, Darw'in, 
Weisman, and others, have propounded theories 
of their own, based on the principle of slow 
progress, involving no essential "break,”— 
whereas De Vries, as we know, in his theory 
of mutation, has advanced the idea that a series 
of sudden or abrupt changes is quite possible, 
and is, in fact, to be observed today in many 
cases of plants and, to a lesser extent, even m 
the lower forms of animal life. 
However evolution may be thought to 
operate, the fact of evolution is certain. As 
a matter of fact, there are various evolutions 
