THE ACTIONS OF FORCES ON ORGANIC MATTER. 3Y 



presence, and from the transformations which they undergo 

 in the body, it may be safely inferred that their chemical 

 affinities are instrumental in working some of the meta- 

 morphoses ever going on. 



The inorganic substance, however, on which mainly depend 

 these metamorphoses in organic matter, is not swallowed 

 along with the solid and liquid food, but is absorbed from 

 the surrounding medium — air or water, as the case may be. 

 Whether the oxygen taken in, either, as by the lowest ani- 

 mals, through the general surface, or, as by the higher ani- 

 mals, through respiratory organs, is the immediate cause 

 of those molecular changes which are ever going on through- 

 out the living tissues; or whether the oxygen, playing the 

 part of scavenger, merely aids these changes by carrying 

 away the products of decompositions otherwise caused; it 

 equally remains true that these changes are maintained by 

 its instrumentality. Whether the oxygen absorbed and dif- 

 fused through the system effects a direct oxidation of the 

 organic colloids which it permeates, or whether it first leads 

 to the formation of simpler and more oxidized compounds, 

 which are afterwards further oxidized and reduced to still 

 simpler forms, matters not, in so far as the general result is 

 concerned. In any case it holds good that the substances of 

 which the animal body is built up, enter it in either an'un- 

 oxidized or in a but slightly oxidized and highly unstable 

 state; while the great mass of them leave it in a fully 

 oxidized and stable state. It follows, therefore, that, what- 

 ever the special changes gone through, the general process is 

 a falling from a state of unstable chemical equilibrium to a 

 state of stable chemical equilibrium. Whether this process 

 be direct or indirect, the total molecular re-arrangement and 

 the total motion given out in effecting it, must be the same. 



§ 15. There is another species of re-distribution among 

 the component matters of organisms, which is not immediately 

 effected by the affinities of the matters concerned, but is me- 



