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ing more widespread each 3'-ear. In Illinois it is known only as 
a greenhouse pest, and our observations indicate that here, at least, 
it is unable to survive the winter in the field. 
The only unmistakable indications of the presence of this root- 
feeding worm are the swellings or enlargements of the roots (Fig. 
20) often referred to by the gardener as root-knots.* These root- 
Fig. 20. Cucumber roots showing galls of a nematode, Hcte- 
rodcra radicicola. (Massacliusetts Experiment Station.) 
knots vary in size and shape, largely according to the number of 
worms present, to their position on the roots, and to the kind of 
plant. The presence of the eel-worms may be indicated by a sickly 
appearance of the plant, by the dying of its leaves, and by its final 
collapse, altho nothing but an examination of its roots can certainly 
*This deformity should not be confused with the club-root of cabbage and 
related plants, which is due to bacterial disease. 
