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it, its own independent nature, so that the total range of activities becomes thus 

 step by step more elastic, less definite, and therefore less predictable ; each 

 element having its own susceptibility to external influence, the equilibrium 

 becomes therefore less stable, and the free energy greater, permitting many and 

 loose combinations, and an increasingly delicate response to the environment. 1 



(6) And though the most striking examples of what I have called the " non- 

 mechanical " are certainly furnished by vital phenomena, still we shall find, if we 

 follow out these transitions in other realms of Nature where the details are 

 more fully known, that "mechanism," in being thus transformed into "higher" 

 categories, thereby acquires such characteristics that it becomes possible to see 

 that life also is itself but another instance of the same transition, and that vital 

 change is thus not something absolutely opposed and foreign to mechanism. 



In the first place, it is possible for a system which in type is purely mechanical — 

 a system whose elements are relatively few and simple — to be so conditioned 2 

 that its total development presents a very long series of most complex phases, far 

 surpassing (in this respect) any living individual or species ; — this occurs when the 

 simplicity of the physical constituents themselves is combined with a great range 

 of variety in the details of their relations. Such a combination, however, demands 

 vast space and long duration, so that its best examples are found in the solar and 

 stellar systems. Here the planetary elements are in themselves of the simplest 

 possible physical character — moving, gravitating bodies ; and yet so delicately 

 graduated are their mutual attractions that the complex and protracted develop- 

 ments irresistibly suggest Vitality. 3 In this connection, again, the analogies 

 presented by the electronic atom and by radio-activity — phenomena purely 

 mechanical — are obvious. 



And conversely, vital phenomena themselves necessarily present one aspect 

 which is undoubtedly " mechanical," and once more disproves any absolute 

 opposition between the two types ; for in principle, and apart from the special 

 details of each particular case, every complete vital cycle has a fixed or 

 " mechanical " aspect — every course of development follows a certain regular 

 order, from which any marked departure is an abnormality 4 ; so that to a 

 Martian — ab extra — the life cycles of a species would appear just as mechanical 

 as a number of clocks — taking the sequences as wholes there would be nothing 

 to distinguish one type from the other. 



(7) But when Time and Space become limited, complex development is 

 possible only with systems whose constituents are at once many in number and 

 diverse in character, 5 of which (excluding psychical and social phenomena), 

 Protoplasm is undoubtedly the principal. As we have seen (ante) so complicated 

 a material system must necessarily possess extreme sensitiveness and instability — 

 it cannot in face of its environment be rigid and unchanging ; and therefore the 

 only question is as to which of two possible courses its changes must follow — 

 whether i.e. its integrity as a purely material system will (under conditions whose 



1 E.g., increasing internal national differentiation brings about more numerous 

 and delicate international relations. 



2 Owing to the "degradation" of energy— see below, par (9). 



3 E.g. Arrhenius, Life of the Universe, and Bickerton, Birth of Worlds and 

 Systems. 



4 " Reproductive processes in the Protozoa, like those in the Metazoa, tend to 

 run in cycles" (Marshall, Physiology of Reproduction, p. 212). 



5 I shall try to show later that such systems are at all possible only as a result 

 of the " degradation " of the universe's energy. 



