lo March. 1910.] Tlic Onion Ed-worm. 167 



A numljer of \'cun<^r jjlants, grown on soil free from infection, were 

 taken and transplanted, one lot being dipped in a solution of lead arsenate, 

 the other l:>eing untreated. They were then planted out in an infected 

 area. In a little over a week all the plants treated with the lead arsenate 

 had died off, probablv owing to the solution being too concentrated. The 

 unti'eated plants did not show any evidence of attack by the eel-worm. 



Our experiments show- that onions transplanted from a sterile seed bed are 

 not liable to attack bv nematodes, unless the bulb be injured in the process 

 of transplantation or bv other agencies. 



Method of Detecting the Eggs of Nematodes in the Soil. 



It is extremelv difficult to detect the eel-warms or their eggs in the 

 soil, more especially is this the case in the black soils of the Drvsdale 

 district. Hundreds of micrO' slides prepared from this soil mav be 

 examined without detecting the presence of either the nematodes or their 

 eggs. Owing to the great amount of labour entailed by the above method 

 of examination, it was necessary to have .recourse to one which would 

 reveal their presence in a quick and satisfactorx manneT. 



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THE OXIOX Kr.L-UOKM IN VAItlDlS STAUKS. (X '■^'^.^ \ ECiOS OK XKM ATOUliS, SIlOVVlNCi TIIK CliNTAlNKU 



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The process adopted b\ Dr. Cobb* of washing the nematodes out of 

 the soil, by mixing with water, and pouring back and forth from one 

 dish to another, allowing the mixture of earth and water to stand until 

 the oaganisms have settled, then pouring off the muddy water, was found 

 to be unsuitable when dealing with the black soils. 



Our first experiments for the detection of the nematodes in the soil 

 w^ere carried out somewhat on bacteriological lines. Boiled onions were 

 taken and the pulp inoculated with small quantities of the affected soil. 

 After an interval of twelve days, an examination of the pulp showed the 

 presence of numerous embryo eel-worms, while the uninoculated pulp 

 remained sterile. The latest method adopted by us is on similar lines. 

 A quantity of soil taken from infested land is placed in a small glass jar, 

 the soil moistened wdth sterile water, and strips of onion leaf free from 

 nematodes laid on the surface, and examined at intervals of a few days. 

 After a period ranging from seven days to a fortnight, the eggs of the 

 eel-worm, if present in the soil, will have hatched out in the vicinity of 

 the leaf. All that is necessary then is to take a small fragment of the 



* Xeiiiiit<iile I'ai'iisites. Misi-ellaneou'- Publifation, Xo. -Jl.i, Dept. of Aur., X.S.W. 



