422 COSMIC J'JULOSOPIIY. [n. n. 



prove that other living things, which are nearly or quite 

 destitute of specialization, may not have their ranks recruited 

 by a fresh evolution from not-living materials. Along with 

 the absence of specialized structure, it may turn out that 

 there is an absence of other characteristics once supposed to 

 be common to all living things. 



This will be more clearly understood as we proceed to 

 consider the change which the last half-century has wrought 

 in the theories of life with which Eedi's doctrine has hitherto 

 been implicated. The hypothesis of a "vital principle" is 

 now as completely discarded as the hypothesis of phlogiston 

 in chemistry, or as the Ptolemaic theory in astronomy : no 

 biologist with a reputation to lose would for a moment think 

 of defending it. The great discoveries concerning the sources 

 of terrestrial energy, illustrated in the foregoing chapter, have 

 made it henceforth impossible for us to regard the dynamic 

 phenomena manifested by living bodies otherwise than as 

 resulting from the manifold compounding of the molecular 

 forces with which their ultimate chemical constituents are 

 endowed. Henceforth the difference between a living and a 

 not-living body is seen to be a difference of degree, not of 

 kind, — a difference dependent solely on the far greater mole- 

 cular complexity of the former. As water has properties that 

 belong not to the gases which compose it, so protoplasm has 

 properties that do not belong to the inferior compounds of 

 which it is made up. The crystal of quartz has a shape 

 which is the resultant of the mutual attractions and repulsions 

 of its molecules ; and the dog has a shape which is ultimately 

 to be explained in the same way, save that in this case the pro- 

 cess has been immeasurably more complex and indirect. Such, 

 in brief, is the theory by which the vitalistic doctrine of 

 Stahl has been replaced. Instead of a difference in kind 

 between life and not-life, we get only a difference of degree, 

 bo that it again becomes credible that, under favouring cir. 

 cumstances, not-life may become life. 



