186 BOAKD OF AGRICULTURE. 



If to the causes already mentioned as increasing the ten- 

 dency to city life we add the easy transportation of food 

 and passengers by steam and horse railroads, it makes the 

 concentration in large cities possible and probable beyond 

 anything known in the ancient world. Some now born will 

 doubtless live to see the time when New York City, with its 

 environs, will contain 10,000,000 of inhabitants, and from 

 2,000,000 to 5,000,000 each in Philadelphia, Chicago, Bos- 

 ton, Cincinnati, St. Louis, San Francisco, and perhaps other 

 cities. All this indicates a still greater waste from city 

 sewage in the future than in the past. 



As before observed, if the soil is not too much exhausted, 

 nature is ever ready to attempt its renovation. She fills up 

 the waste places with the lower forms of vegetation where 

 the higher forms or wholesome plants will not grow, and 

 these by their decay tend* to increase the fertility of the soil 

 and prepare it for a more useful growth. Thus the mosses, 

 lichens, hardback and birches take possession of worn-out 

 soil, hold what is left of the humus, gradually add more, and 

 finally work it back to fertility. But as there is a point in 

 organic derangements beyond which nature loses her power 

 or refuses to act and the patient dies, so when by continual 

 cropping the organic material in the soil is removed, leaving 

 but little except the mineral constituents of the earth, nature 

 refuses to endure this repeated abuse and withholds her 

 beneficent labors. The poverty of the soil will then become 

 its own destruction. The sun will burn out and the rains 

 will leach out any fertility yet remaining, and the winds will 

 complete the work by making it a desert of moving sands ; 

 and judging by the past, if the soil is once destroyed over an 

 extensive area there is no redemption. 



Under the present prodigal waste of fertility in our coun- 

 try this result is only a question of time. The enormous 

 demand from Western Europe, the waste of our cities, the 

 application of improved implements and horse and steam 

 power to agriculture, the increased facilities for transporta- 

 tion both by land and water, will tend to bring the same 

 result to us more rapidly than it came to the ancient world, 

 and make the desolation, if possible, more complete. 



There are instances where a high state of civilization has 



