18 THE INVISIBLE WORLD 



one ounce of soil, depending on its condition, are 

 found from 7,000 to 7,000,000,000. It is estimated 

 that every ounce of soil on the land surface of the 

 earth to the depth of four feet, contains, on the 

 average, about 10,000. 



Water is quite as favorite a dwelling place for 

 these beings. A quart of water just condensed 

 from vapor contains 1,000. A quart of rain water, 

 7,000. A quart of spring water, 200,000. A quart 

 of ordinary river water, 1,500,000. A quart of 

 river water just below a populous city, 13,000,000. 

 A quart of sewer water, 100,000,000. 



In all the air, soil and water of the earth, what 

 a universe of these unseen beings. Count up every 

 living thing in the visible world, all the trees of 

 the forests, grasses and flowers of the field, fishes 

 of the seas, birds of the air, reptiles and worms 

 that crawl, animals domestic and wild, and all the 

 insects teeming everywhere, add all these num- 

 bers together, and you will need to multiply the 

 result by millions upon millions, to equal the num- 

 bers of microbes. 



