THE BIOLOGY OF DAILY LIFE. 



CHAPTEE I. 



THE LAW OF INTERCHANGE. 



IT is a long known, well established and now 

 universally acknowledged fact, that the mineral, 

 vegetal, and animal kingdoms bear a definite re- 

 lation to each other. Plants are intermediary as 

 regards sustenance, between minerals and animals 

 a necessary link in the chain of being. 



This has long been known, and is now a common- 

 place a household word of Biological science. 



Professor Asa Gray, in his " Structural and 

 Systematic Botany" (New York, 1862), a standard 

 work in its day, says (page 23) : 



"Plants live directly upon the mineral 

 kingdom. They alone convert inorganic or 

 mineral into organic matter; while animals 

 originate none, but draw their whole sus- 

 tenance from the organized matter which 

 plants have thus elaborated." 



In a standard medical work of the present day 

 (Quain's Diet, of Medicine, 1886), Dr. Pavy writes 

 in his article on " Aliment" (p. 81) : 



"The aliment of organisms belonging to 

 the vegetable class is derived from the in- 

 organic kingdom. Under the influence of the 

 sun's rays the inorganic principles are applied 

 to growth, and constructed into organic com- 



