Soil Sickness Due to Parasites 49 



Symptoms. The disease is characterized by a 

 swelling on the roots, showing itself in small knots 

 formed either singly or in pairs, or in strings, giving 

 the affected root a beaded appearance (fig. 8 a, b). 

 Sometimes, however, the swellings are so large that 

 they may be mistaken for the root nodules (fig. 8 c) 

 of legume plants, which occur normally in great 

 abundance. Infested plants usually linger for a long 

 time, but they can be distinguished by a thin growth 

 and yellow sickly looking leaves and stems. 



Distribution. The eelworm seems to be of world- 

 wide distribution, being found in Europe, Asia, 

 Australia, and both North and South America. 

 And yet, there are many localities in which this pest 

 has never been known. 



Life History. The eelworm is a very minute worm, 

 seldom exceeding one twenty-fifth of an inch in 

 length. It is semi transparent, so that it cannot be 

 easily detected by the naked eye. In searching for the 

 eelworm, break a fresh knot. Close examination will 

 reveal two types of worms: a spindle-shaped worm, 

 the male (fig. 8 g, h), and a pearly white pear-shaped 

 organism, the female (fig. 8 e, f), firmly embedded in 

 the gall tissue. The female is very prolific, depositing 

 no less than 400 to 500 eggs during her lifetime. 

 The eggs are whitish (fig. 8 d), semi transparent 

 bean-shaped bodies, and too small to be noticed 

 without the aid of a magnifying glass. The time 

 which elapses until the eggs hatch depends largely 

 upon weather conditions. In warm days the eggs 

 hatch sooner than in cold days. Upon hatching, the 



