DOMESTICATED EARTHWORMS 85 



and growth of earthworms. We commonly develop culture beds 

 with concentrations of as many as 3,000 worms per cubic foot, 

 with corresponding results in the production of humus. To 

 breed worms in such great numbers in limited space, we must, 

 of course, provide food material and soil-building elements for 

 them to work with. It should always be borne in mind that 

 worms live on the organic contents of the soil. Therefore, if 

 the soil furnished them is deficient in organic material, the 

 worms cannot live in it. They do not secure any nutrition from 

 the purely mineral content of the soil, but only from the or- 

 ganic content that has been derived through life processes. 



In the adaptation of the earthworm as a controlled servant 

 of man, the elements of chance must be eliminated and results 

 must be measured in units of time. While we may build soil 

 for future generations, we want to have the benefit of the soil 

 here and now, and this is the reason for intensive breeding of 

 earthworms. Working with the sure methods of definite pur- 

 pose and knowledge, we may achieve results within a few months 

 which would otherwise require many decades to accomplish, 

 were we to wait on the leisurely processes of nature, which 

 take no account of time. 



In using the term "domesticated earthworm," we are re- 

 ferring to a breed of earthworms which has been developed and 

 modified by selective breeding and feeding over a period of 

 several years, to meet the requirements for intensive use in 

 horticulture and agriculture. The original object of the ex- 

 perimental work which led to the development of the domesticated 

 earthworm was to eliminate the elements of chance which are 

 encountered in dealing with the exceedingly numerous varieties 

 of native earthworms ; to speed up results to meet the demands 

 of practical people under all conditions and environments, both 

 city and country; and, above all, to develop an earthworm which 

 would be adaptable to every kind of soil and food and one which 

 could be changed readily from one environment to another. The 

 ordinary native earthworm is a slave to the environment into 



