lyo 



Journal of A(;rh-///i//rc 



lo AFarch, 1910. 



Onion-growers are special!}- recommended to keep a look out for plants 

 similar in appearance to those illustrated. The}- should immediately be 

 pulled ufj and destroyed by burning. This is a wise precaution, for if 

 allowed to .remain in the soil, on the decav of the plant, the eggs fall into, 

 the ground and may thus spread over a considerable area to further pro- 

 pagate the disease. 



The onion eel-worm Tylcnchus 

 devastatrix has been so frequently 

 described that a short review of 

 the principal points of its anatomy 

 and life history is all that is re- 

 quired here. 7'. devastatrix be- 

 longs the family Anguillulida^ 

 of the sub-order N ematoda. It 

 is filiform in shape, and of small 

 size, averaging only i-25th of an 

 inch in length, and i -500th of an 

 inch in width. It lives and repro- 

 duces in leaves and stems (never 

 in roots, except in the case of 

 hops). — (Percival.) In damp soil 

 they also multiply, provided there 

 is a sufficiency of decaying veget- 

 able matter. The mouth is pro- 

 vided with a spine or spear, which 

 works to and fro and assists the 

 animal to bore into the tissues of 

 a plant. The sexes are distinct, 

 the males being slightly smaller 

 '' than the females. The females are 

 \iviparous and o\iparous. The 

 number of eggs deposited varies ; 

 compared with the eggs of other 

 members of this family they are 

 comparatively large, measuring 

 I -300th of an inch in length and 

 I -Sooth of an inch in width. 

 The eggs are surrounded by a 

 semi-transparent membrane of a 

 chitinous nature, which is ex- 

 tremely resistant to chemicals, 

 drying, and changes of tempera- 

 ture, though a moist heat of 

 150" F. complete! V destrovs their 

 vitalitv. 



NEMATODES AND EftCiS. (AFTER KITZEJIA BOS 



1. Kemale Eel-wonii. 



(f/) Spear at head enrl. (i) Median suckinn Imlli. 

 ((■ 1/) Intestine, (e) Commencement iif o\ary, 

 with numerous ovules of egg'. 



2. Male Eel-worm. 



3. Anterior portion of Eel-worm not fully developid. 



(«) Spear, (i) Median sucking- hulb. (<•) Beginning 

 of intestine 



4. Anterior portion of same, taken from wheat plant. 



5. Eel-worms from Hyacinth, dried and rolled together. 

 6 and 7. Egg- with young Eel-worm. 



8. Young- Eel-worm newly hatched. 



9. Eg-g- before formation of endjryu. 



Summary. 



The heavy rains which occurred during the period of treatment greatlv 

 militated against the success of the experiments, the chemicals being washed 

 out of the soil or rendered so dilute as to become u.seless for killing the 

 young worms. Though the experiments were of little value from a 

 grower's stand-point, still the information gained as to the life and habits 



