68 THE PHYSICAL GEOGRAPHY OF THE SEA. 



supply of food designed for living creatures is thrown ; or, in one 

 word, it is itself the food, in its simple form, of all living crea- 

 tures. The animal grinds down the fibre and the tissue of the 

 plant, or the nutritious store that has been laid up within its cells, 

 and converts these into the substance of which its own organs are 

 composed. The plant acquires the organs and nutritious store 

 thus yielded up as food to the animal, from the invulnerable air 

 surrounding it." 



" But animals are furnished with the means of locomotion and 

 of seizure — they can approach their food, and lay hold of and 

 swallow it ; plants must wait till their food comes to them. No 

 solid particles find access to their frames ; the restless ambient 

 air which rushes past them loaded with the carbon, the hydrogen, 

 the oxygen, the water — every thing they need in the shape of sup- 

 plies is constantly at hand to minister to their wants, not only to 

 afford them food in due season, but in the shape and fashion in 

 which alone it can avail them." 



90. There is no more worthy or suitable employment of the 

 human mind than to trace the evidences of design and purpose 

 in the Creator, which are visible in many parts of the creation. 

 Hence, to the right-minded mariner, and to him who studies the 

 physical relations of earth, sea, and air, the atmosphere is some- 

 thing more than a shoreless ocean, at the bottom of which his 

 bark is wafted or driven along. It is an envelope or covering for 

 the dispersion of light and heat over the surface of the earth ; it 

 is a sew^er into which, w4th every breath we draw, w^e cast vast 

 quantities of dead animal matter ; it is a laboratory for purifica- 

 tion, in which that matter is recompounded, and wrought again 

 into wholesome and healthful shapes ; it is a machine (§87) for 

 pumping up all the rivers from the sea, and conveying the w^aters 

 for their fountains on the ocean to their sources in the mount- 

 ains. 



91. Upon the proper working of this machine depends the well- 

 being of every plant and animal that inhabits the earth ; there- 

 fore the management of it, or its movement, or the performance 

 of its offices, can not be left to chance. They are, we may rely 

 upon it, guided by laws that make all parts, functions, and move- 

 ments of the machinery as obedient to order as are the planets in 

 their orbits. 



