24 Diseases of Greenhouse Crops 



(fig. 4, a-e.). Close examination will reveal two 

 types of worms; a spindle shaped worm, the male, 

 and a pearly white pear shaped organism, the fe- 

 male, firmly embedded in the gall tissue. The fe- 

 male is very prolific, depositing no less than 400 to 

 500 eggs during her lifetime. The eggs are whitish, 

 semi-transparent, bean shaped bodies, and too small 

 to be noticed without the aid of a magnifying glass 

 (fig. 4, f.). The time which elapses until the eggs 

 hatch (fig. 4, f-u) depends largely upon weather 

 conditions. In warm days the eggs hatch sooner 

 than in cold days. Upon hatching, the young larvae 

 either remain in the tissue of the host plant in which 

 they emerge, or, as is more often the case, leave the 

 host and enter the soil. This is the only period 

 during which the worms move about to any great 

 extent in the soil, where they either remain for 

 some length of time or immediately penetrate an- 

 other root of the host. The nematodes in most cases 

 become completely buried in the root tissue, estab- 

 lishing themselves in the soft cellular structure which 

 is rich in food. The head of the worm is provided 

 with a boring apparatus consisting of a sharply 

 pointed spear, located in the mouth. This struc- 

 ture not only aids it in getting food but is also val- 

 uable in helping the young worms to batter through 

 the cell walls before becoming definitely located. 

 The two sexes during the development are indis- 

 tinguishable up to fifteen or twenty days, both be- 

 ing spindle shaped. In the molting or shedding of 

 the skin, there is a marked change in the case of the 



