4O THE LIVING WORLD. 



or group of theories has led to a belief in the general 

 efficiency of natural law to account for natural phe- 

 nomena ; and from this conception has arisen the 

 claim that there must have been a natural origin of 

 life. While then biologists have somewhat reluc- 

 tantly given up their beliefs in the present possibility 

 of spontaneous generation, many of them even the 

 more strenuously assert that at some time, in some 

 way, life must have arisen from the non-living. 



Speculations as to a Mechanical Origin of Life. 



Unable, therefore, to obtain direct evidence either 

 for or against its proposition of a natural origin of 

 life, science endeavors to meet the question by 

 speculation. Having shown that vital processes are 

 closely related to chemical and physical conditions, 

 suggestions as to a possible causal connection be- 

 tween the two are of some significance. Speculations 

 as to the origin of life can, therefore, hardly be 

 called absurd, though they are almost unfounded in 

 fact. Although they cannot be regarded as having 

 much value, nevertheless modern scientific beliefs 

 are in a measure founded on them. 



We may pass over as irrelevant the suggestion 

 that life may have been brought into the world by 

 meteors. This does not of course assist in the slight- 

 est degree in solving the question of the origin of 

 life. While different thinkers will hold different 

 views upon the general question, nearly all will de- 

 pend upon unknown conditions of the past for aid. 

 A line of speculation something like the following 

 would probably not be far from expressing the gen- 



