SOIL FERTILITY 



(s. s. 481) 170 



57- M. acutus, n. sp. CEsophagus bulbous at first, the swelling being prolate. 

 Intestine about 10 cells in girth. The arcuate conoid tail is practically acute. There 



is a pair of 2.6 

 sublateral, 2.7 



7.5 23. 



94. 



8.1 



Hi. 



3.2 3.3 3.4 



innervated papillae near the beginning of the pos- 

 terior third of the tail. Anus not raised. Fig. 68. 

 Found about the roots of rhubarb in loose, 

 brown, sandy soil, Arlington Farm, Virginia, 

 U. S. A. Nemativorous. One specimen was ob- 

 served which had swallowed another mononch. 

 This is one of the most instructive forms. It is 

 desirable that the more minute structural details 

 of nemas be very carefully investigated with a view 

 to increasing our knowledge of their comparative 

 anatomy. The different parts of the digestive or- 

 gans of nemas, small as they are, are as pro- 

 foundly modified in harmony with the nature of the 

 food as those of higher animals. The digestion of starch requires a different 

 organic mechanism from that for digesting meat. The nemas have specialized to 

 a high degree in the matter of food, and their digestive organs are correspondingly 

 diversified. 



NEMAS AND SOIL FERTILITY 



No one with a grain of imagination can engage in such studies as the 

 foregoing without sooner or later asking himself questions of a general 

 nature concerning the biology of the soil, for he gradually comes to sec 

 how almost infinitely numerous and varied are the organisms inhabiting 

 it; a population in which the nemas are but an element. The answers to 

 these questions will lead to a new view of soil fertility. 



The revolution wrought by Liebig's ideas concerning the chemistry of 

 the soil spent itself only to show us that, grand as it was, it was little 

 more than an overture. Subtler forces and more intricate relationships 

 than any indicated in these earlier conceptions must be considered. We 

 now see, or are beginning to see, that the value of manure and of the ro- 

 tation of crops is to be explained not simply on the basis of the exhaus- 

 tion of certain elements in the soil, but also, and probably in some in- 

 stances mainly, on the basis of an opposite process, an accumulation of 

 certain organisms and substances in the soil. Who knows but that the 

 existence of annuals may be due in some measure to this latter fact? May 

 not these elaborate provisions for the distribution of the seeds of annuals 

 be in some measure a means of escaping these accumulated hostile forces 

 in the soil ? 



After all the word Agriculture is more or less of a misnomer. We 

 cultivate, not so much the field, as plants. What we are really after is 

 sunshine, for we are lost unless we can convert our infinitesimal part of 

 the energy of this nearest star into food, clothing and shelter. This we 

 do by utilizing the life forces of certain plants and animals, and these are 

 not so few as we dreamed in our older philosophy, for none of our 

 "domesticated organisms" can any longer be considered by itself. Every 



