54 THE CUCUMBER AND TOMATO EELWORM. 



into an embryonic worm is similar to that of a living cell in the 

 growing part of a plant — />., the nucleus and protoplasmic con- 

 tents divide, a cell-wall is formed in the division, so that the 

 mother cell or egg (Fig. 3, a) now contains two daughter cells 

 (Fig. 3, d). By similar divisions these daughter cells again divide 

 (Fig. 3, c, d)^ until a mass of cellular tissue is formed (Fig. 4, a), 

 from which the young embryonic eelworm is ultimately developed 

 (Fig. 4, b, r, d). The embryo remains for about two days in the 

 egg and then comes out (Fig. 5). 



The young wormlet is about the twelve-thousandth part of an 

 inch in diameter, and is thread-like in shape, tapering gradually to 

 a blunt head-end, and gently into a slender needle-like tail. This 

 is known as the larval stage. During the larval stage males and 

 females are both alike in appearance — i.e.., eel-shaped, and are 

 easily mistaken for Tyle?ichus devastatrix (the stem eelworm). 



When the eelworm leaves the egg, it generally finds itself 

 imprisoned within one of the cells of the plant. As soon as the 

 supply of food in the cell is exhausted, the worm has either to pass 

 out of the cell or die of starvation. It can, however, pass from 

 cell to cell by battering in the cell-wall, which it does by means of 

 the spear. 



Sometimes hundreds of worms are liberated by the decay of 

 the root gall ; these find a fresh portion of root, and enter it by 

 piercing through the cell-walls. The plant is not able to expel the 

 intruder, but it tries to repair the injury by the development of 

 fresh cells ; hence the formation of the nodules or galls on the 

 roots. After a time the young worms come to rest, and their 

 bodies begin to enlarge, the posterior end becoming larger than 

 the anterior portion (Fig. 6). The male, which up till now has 

 been similar in appearance to the female, undergoes various 

 changes and modifications, ultimately assuming the eelshape again 

 (Fig. 7), while the female undergoes a transformation which differs 

 in every respect from the male. The female, instead of returning 

 to the eel shape, continues to enlarge (Fig. 8), its tail is cast off, 

 and its reproductive organs are developed. The male, after wan- 

 dering about for a time in the tissues of the plant or in the soil, 

 finds its mate and pairs, then dies. 



The eggfc begin to be develoi>ed while the female cyst is com- 



