CHAPTER I. 



ORGANIC MATTER. 



§ 1. Of the four chief elements which, in various com- 

 binations, make up living bodies, three are gaseous' under 

 all ordinary conditions and the fourth is a solid. Oxygen, 

 hydrogen, and nitrogen are gases which for many years defied 

 all attempts to liquefy them, and carbon is a solid except 

 perhaps at the extremely high temperature of the electric arc. 

 Only by intense pressures joined with extreme refrigerations 

 have the three gases been reduced to the liquid form.* There 

 is much significance in this. When we remember how those 

 redistributions of Matter and Motion which constitute Evo- 

 lution, structural and functional, imply motions in the units 

 that are redistributed; we shall see a probable meaning in 

 the fact that organic bodies, which exhibit the phenomena 

 of Evolution in so high a degree, are mainly composed of 

 ultimate units having extreme mobility. The properties of 

 substances, though destroyed to sense by combination, are 

 not destroyed in reality. It follows from the persistence of 

 force, that the properties of a compound are resultants of the 

 properties of its components — resultants in which the pro- 

 perties of the components are severally in full action, though 

 mutually obscured. One of the leading properties of each 



* In this passage as originally written (in 1 862) they were described as 

 incondensible ; since, though reduced to the density of liquids, they had not 

 been liquefied. 



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