NON-PROTOZOAN FAUNA OF SOIL 349 



nematode Tylenchus tritici, and various others. 18 Some of them attack 

 a great variety of plants. C. radicicola, for example, attacks about 

 five hundred kinds of plants. This organism flourishes best in high- 

 sandy soils, which are moist and warm. It attacks cotton, beans, 

 celery, eggplants, potatoes, lettuce, peas, tomatoes, cowpeas, soybeans, 

 nursery stock, weeds, ornamental plants and various field crops. Some 

 plants, however, are not attacked. Heterodera schachtii attacks pota- 

 toes, sugar beets, etc., and may prove to be very injurious. 19 Tylen- 

 chus dipsaci attacks clover, alfalfa, and other crops, ornamental plants, 

 etc. 20 



The nematodes are represented in the soil by a large number of 

 genera. 21 It is sufficient only to enumerate some of the most common : 



Iota (syn. Hoplolaimus) found in swamp and acid soils, on the roots of trees. 

 Tylenchus, found in peat and moist soils, on plant roots; many parasitic 



species. 

 Aphelenchus, found in various soils, many species parasitic. 

 Isonchus, found on the roots of the cotton plant. 

 Dorylaimus, omnivagus, very abundant in the soil. 

 Actinolaimus, found in peat bogs and marshy soils. 

 Ironus, occurs to a limited extent in very moist soil. 

 Mononchus, predacious nematode, represented in the soil by many species, 



cosmopolitan. 

 Diplogasier, found in moist soils. 

 Cyatholaimus, found in moist soils. 

 Plectus, omnivagous, well distributed in the soil. 

 Rhabditis, cosmopolitan, some species microbivorous, well distributed in 



the soil. 



18 Marcinowski, K. Parasitisch und semi-parasitisch an Pflanzen lebende 

 Nematoden. Arl. Biol. Anst. Land. u. Forst., 7: 1-192. 1909. 



19 Zimmermann, H. Nematodenbefall (Heterodera) an Kartoffeln. Ztschr. 

 Pflanzenkrank., 30: 139-145. 1920. 



20 Goodey, T. On the susceptibility of clover and some other legumes to 

 stem-disease caused by the eelworm, fylenchus dipsaci, syn. devastatrix Kuhn. 

 Jour. Agr. Sci., 12: 20-30. 1922. Ritzema-Bas, J. Les nematodes parasites 

 des plantes cultivees. VI. Int. Congr. Inst. Agr., Paris, 2: 306-312. 1900. 

 The cultivation of plant pathogenic nematodes is discussed by Byars, L. P. 

 Preliminary notes on the cultivation of the plant parasitic nematode, Heterodera 

 radicicola. Phytopath., 4: 323-326. 1914; Hilgermann and Weissenberg, R. 

 Nematodenziichtung auf Agarplatten. Centrbl. Bakt., I, Orig., 80: 467-472. 

 1918; Berliner, E., and Busch, K. fiber die Ziichtung des Rtibennematoden 

 {Heterodera schachtii Schmidt) auf Agar. Biol. Centrbl., 34: 349. 1914. 



21 A detailed classification of nematodes is given by Cobb, N. A. Free-living 

 nematodes. Fresh-water Biology by Ward and Whipple, 1918, p. 459-505. 

 Micoletzky, 1921 (p. 347) and De Man, 1922 (p. 348). 



