NON-PROTOZOAN FAUNA OF SOIL 347 



animals and those that are entirely saprophytic. Different soils may 

 be found to contain large and varying numbers of nematodes as shown 

 in the following summary: 10 



Morris 11 also found large numbers of nematodes in the soil, the great- 

 est number occurring at a depth of two to three inches in manured 

 soil and four to five in unmanured soil. Four to five times as 

 many nematodes were found in the manured as in the unmanured 

 soil. According to Micoletzky, 12 the soil and fresh water nematodes 

 embrace 75 genera and 525 species. Half as many nematodes were 

 found in the winter as in the summer. The abundance of these or- 

 ganisms in the soil is determined by moisture, abundance of plant 

 life and plant residues, and other microorganisms. The different 

 nematodes vary in their nutrition: 



1. Some, like Rhabditis, Diplogastcr, Cephalobus, feed at least partly on de- 

 composing organic matter which results from the activities of the bacteria, as 

 well as upon the bacteria themselves, and also upon fungi and algae; this is also 

 true of such forms as Monohystera and Bunonema (No. 146, PI. XVIII). 



10 Steiner, G., and Heinley, H. The possibility of control of Heterodera 

 radicicola and other plant injurious nemas by means of predatory nemas, es- 

 pecially by Mononchus papillatus Bastian. Jour. Wash. Acad. Sci., 12: 367-386. 

 1922. 



"Morris, 1922 (p. 342). 



12 Micoletzky, H. Die freilebenden Erdnematoden mit besonderer Beruck- 

 sichtigung der Steiermark und der Bukowina, zugleich eine Revision samtlicher 

 nicht mariner, freilebender Nematoden in Form von Genus-Beschreibung und 

 Bestimmungsschliisseln. Arch. Naturg., 87: 1-650. 1921. Zur Kenntnis tro- 

 pischer, freilebender Nematoden aus Surinam, Trinidad und Ostafrika. Zool. 

 Anz., 64: 1-28. 1925. Die freilebenden Suszwasser- und Moornematoden Da- 

 nemarks. D. Kgl. Danske Vidensk. Selsk. Skr. Afd. 8 R., x, 2. Kobenhavn. 

 1925. 



