I 



What are Aiiwials and Plants f Z^Z 



of fossil remains : the first, by its deposits ; the second, by its 

 eroding agency. The Mississippi has formed thirty thousand 

 square miles of deposits, which are in places several hundred 

 feet thick. The Ganges carries down yearly to the sea as 

 much mud as could be carried down by 730,000 ships, each 

 of 1400 tons burthen. The eroding and destructive agency 

 of water is, on the other hand, notorious. 



Having acquired these preliminary notions concerning 

 the inorganic or non-living world, we may next review such 

 contrasts as may be drawn between it and the living world of 

 animals and plants considered as one whole. 



I. Now, in the first place, some inorganic substances are 

 fluid and some solid, some moist and some dry ; but every 

 living creature, without exception, is more or less fluid, and 

 composed to a greater or less degree of water, especially its 

 more actively vital or growing parts. 



Thus, in the human brain, seventy out of every hundred 

 parts are composed of water, and in the jelly-fish no less than 

 ninety-nine parts out of a hundred are so composed. 



II. Many inorganic substance, such as crystals, are 

 bounded by flat surfaces and straight lines, but living 

 creatures have bodies which are bounded by curved surfaces 

 and lines. 



III. The chemical composition of inorganic substances is 

 most various ; some, like gold, consist of but a single element ; 

 others, like water, of two elements ; others of several and very 

 different ones. 



All living bodies, on the other hand, are of very uniform 

 chemical composition, as they invariably consist of oxygen, 

 hydrogen, and carbon, together with the element nitrogen — 

 the unstable nature of which has already been referred to in 

 speaking of the inorganic compounds containing nitrogen, 

 which thus seems a fitting element to enter into the com- 

 position of anything so prone to change as is living matter. 



