

NATUEE AND OKIGIN OF LIFE. 19 



the wider scope of philosophy. But we hold that the 

 various aspects cannot be described in the same terms, 

 that they neither overlap nor break into each other's 

 continuity. They are one-sided abstractions based on a 

 reality, with the ultimate nature of which it is not the 

 function of natural science to deal. 



But, it will be asked, if life is thus correlated with a 

 physico-chemical process, why cannot living substance 

 be made in the laboratory ? The answer is that the ex- 

 pectation is premature, perhaps never to be realised. 

 Since we are still ignorant of the intimate structure of 

 the proteins, we can hardly be expected to manufacture 

 them. Moreover, it would not be sufficient to make one 

 or even several such compotinds, but the whole chain of 

 growing complexity. If the machine is to work, the 

 mechanism must be complete. There is, also, a long 

 history behind even the simplest organism found at the 

 present day ; there must be a vast difference between 

 the very simplest of these and the initial stages in the 

 evolution of protoplasm. It would be as absurd to ex- 

 pect an experimenter to build up an organism in a labora- 

 tory as, for instance, to expect a refined civilisation to 

 arise in a day among the savages of Central Africa. 

 Great advances have already been made in the synthesis 

 of organic compounds of carbon and nitrogen ; but if 

 any stage in the development of living substance were 

 artificially made, it would probably be so different from 

 the protoplasm of modern plants and animals that we 

 should scarcely recognise it as living at all, even if we 

 had it before us. 



An attempt to reconstruct in imagination what we 

 believe may have been the history of the origin of living 

 matter may be made not altogether without profit. 



Before the principle of the continuity of life, to which 

 we shall refer later, was established, it was thought that 

 living things arose spontaneously from organic com- 

 pounds. Moulds, the bacteria of putrefaction and fer- 



