THE PHOSPHORUS CYCLE 185 



bacterial activity, as outlined in a preceding chapter. This is taken 

 up by the living plant and deposited either as organic or inorganic 

 phosphorus compounds within the plant tissues. The plant tissues, 

 if eaten by animals, yield phosphorus to the animal to be laid down 

 in the body of the animal as organic or inorganic compounds. The 

 excreta of animals always contain phosphorus in both organic and 

 inorganic forms. The inorganic phosphorus is readily utilized by 

 plants and again starts on its cycle. However, the organic and 

 animal residues must be mineralized by bacteria before they can be 

 utilized again by plants. Microorganisms split oft' the carbonaceous 

 material and the phosphorus is liberated mainly in the form of 

 phosphates. Under some conditions mold action may give rise to 

 small quantities of phosphin which must be again oxidized before 

 being available to higher plants. In either event, the resulting 

 phosphate is now ready to start on its cyclic journey through the 

 plant and animal organism. This is dramatically outlined for a 

 phosphorus atom by one writer as follows : 



'Where was I born? Ah, that I cannot tell you. It was far, 

 far away from here, deep in the endless abyss of space, at an epoch 

 so distant that even the earth on which you live had not been formed 

 as yet; not even the great sun, now blazing in his glory, nor any of 

 the innumerable multitudes of stars of the great universe now 

 shining in the sky, had as yet come into being. No, they were mere 

 cold whiffs of invisible vapor, scattered over all space, remnants of 

 worlds vanished seons before this great universe began. Out of the 

 vast I came, born into that great sea of ether which stretches 

 unbroken from star to star through all the endless depths of space. 

 Some vast change, some murmuring and stirring of gigantic forces 

 in its bosom, forces scarce known, scarce dreamt of, but working 

 there in irresistible might, first brought me into being, and I hung 

 suspended in the great void. It was utterly cold and utterly dark, 

 and gleaming afar in the distance I could see the myriad fires of the 

 great worlds and suns of space shining at me through the darkness. 

 How long I hung in the void I know not. It was millions upon 

 millions of years. Then atoms began to gather round me, stream- 

 wise, coming from afar in phosphorescing torrents, and I perceived 

 that I already formed part of a mighty mass of gas, a huge nebula, 

 which stretched its gigantic arms out for millions of miles, like vast 

 flaming swords, through the darkness of space. And so I hung for 

 seons of time, w r hile atom after atom in an endless stream flashed 

 past me in the gloom, while the great nebula slowly drew together 

 in its glory, and began to take shape and form. Then the tempera- 

 ture began to rise in leaps and bounds, it grew stifling hot, and great 

 lightnings flashed and quivered about me, and we atoms crowded 

 more and more together, colliding, whirling, flying. Each second I 

 smote a thousand million atoms and at each collison my motion grew 



