MOVEMENT 



motion which are peculiar to organic Hfe, and a com- 

 parison of them with the corresponding motions of in- 

 organic bodies. 



The science of motion, or mechanics, is now taken in 

 very different senses: (i) in the widest sense as a phi- 

 losophy of life [generally called mechanism or mechanic- 

 ism in England], equivalent to either monism or ma- 

 terialism; (2) in the stricter sense as the physical science 

 of motion, or of the laws of equilibrium and movement 

 in the whole of nature (organic and inorganic); (3) in 

 the narrowest sense as part of physics, or dynamics, 

 the science of moving forces (in opposition to statics, 

 the science of equilibrium; (4) in the purely mathemat- 

 ical sense as a part of geometry, for the mathematical 

 definition of magnitudes of movement; and (5) in 

 the biological sense as phoronomy, the science of the 

 movements of organisms in space. However, these 

 definitions are not yet universally adopted, and there 

 is a good deal of confusion. It would be best to follow 

 the lead of Johannes Miiller, as we are going to do here, 

 and restrict the name phoronomy to the science of the 

 vital movements which are peculiar to organisms, in 

 contrast to kinematics, the exact science of the inorganic 

 movements of all bodies. The real material object of 

 phoronomy is the plasm, the living matter that forms the 

 material substratum of all active vital movements. 



On our monistic principles the inner nature of organic 

 life consists in a chemical process, and this is deter- 

 mined by continuous movements of the plasma-mole- 

 cules and their constituent atoms. As we have already 

 considered this metabolism in the tenth chapter, we 

 need do no more here than point out that both the gen- 

 eral phenomena of molecular plasma-movement and 

 their special direction in the various species of plants 

 and animals can be reduced in principle to chemical laws, 

 and are subject to the same laws of mechanics as all 



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