348 FOOT-NOTES TO EVOLUTION. 



But can we give them belief ? Let us pass by the 



doctrine of monism, with which science can not concern 



itself. What of the corollaries ? Spon- 



pontaneous taneous generation, for example, has 



generation not , i ^ • r 



science been the basis of many experiments. 



Like the transmutation of metals, it 

 seems reasonable to philosophy. The one idea has 

 been the will-o'-the-wisp of biology as the other has 

 of chemistry. We know absolutely nothing of how, if 

 ever, non-life becomes life. So far as we know, genera- 

 tion from first to last has been one unbroken series — all 

 life from life. We have no reason to believe that spon- 

 taneous generation exists under any conditions we have 

 ever known. We have likewise reason to believe that if 

 it exists at all we have no way of recognising it. The 

 organisms we know have all had a long history. Even 

 the simplest ever examined shows traces of a long an- 

 cestry, a long process of natural selection, and of many 

 concessions to environment. We know of no life that 

 does not show such concessions. We know no creature 

 that does not show homologies with all other living be- 

 ings whatsoever. So far as this fact goes, it tends to 

 show that all life comes from one common stock, a single 

 generation or creation. If this be true, spontaneous 

 generation, whatever it may be, is not a phenomenon of 

 frequent occurrence. 



If life does now appear without living parentage, if 

 organisms fresh from the mint of creation are now devel- 

 oped from inorganic matter, they are so simple that we 

 can not know them. They are so small that we can not 

 find them. They would be made, we may suppose, each 

 of a small number of molecules. If there is truth in the 

 calculations of Lord Kelvin and others, that a molecule 

 in a drop of water is as small as a marble in comparison 

 with the earth, then we may not look for these creatures. 



