CHAPTJER X 



THE CARBON, NITROGEN, SULFUR, AND 

 PHOSPHORUS CYCLES 



Plants contain ten essential elements, and these elements found 

 in the body of the plants or animals today are the same as those 

 which constituted the organic world thousands of years ago. But 

 between these dates they have played many parts, or, in the words 

 of Duncan, "We believe — we must believe in this day — that 

 everything in the universe of world and stars is made of atoms, 

 in quantities x, y, and z, respectively. Men and women, mice 

 and elephants, the red belts of Jupiter and the rings of Saturn, 

 are one, and all but evershifting, ever varying, swarms of atoms. 

 Every mechanical work of earth, air, £re, and water, every crim- 

 inal act, every human deed of love or valor: what is it all, pray, 

 but the relation of one swarm of atoms to another? 



"Here, for example, is a swarm of atoms, vibrating, scintillant, 

 martial — they call it a soldier — and, anon, some thousands of 

 miles away upon the South African veldt, that swarm dissolves — 

 dissolves, forsooth, because of another little swarm — they call it 

 lead. 



"What a phantasmagoric dance it is, this dance of atoms ! And 

 what a task for the master of the ceremonies. For, mark you, 

 the mutabilities of things. These same atoms may come together 

 again, vibrating, clustering, interlocking, combining, and there 

 results a woman, a flower, a blackbird, or a locust, as the case may 

 be. But tomorrow again the dance is ended, and the atoms are 

 far away 5 some of them in the fever germs that broke up the 

 dance, others are the green hair of the grave, and others are blown 

 about the Antipodes on the wings of ocean, and the eternal ever- 

 changing dance goes on." 



Importance of Bacteria in Cycles. — In this building up and 



