ROOT-KNOT EELWORM. 105 



observer from the fear of either misleading, or of over-criticism of his 

 long and careful work. 



Such, however, being the case, I now append only the later 

 series of observation, which were sent me in October. These were 

 made on both Tomatoes and Cucumbers, and the effect was much the 

 same in each case. In the various returns, the most hopeful appears 

 to be that of carbolic acid, but of this my observer remarks : — " As I 

 expressed to you before, although carbolic acid will be effective in a 

 field if properly mixed, I have very strong doubts about people 

 succeeding in greenhouses, on account of the very many crevices in 

 which the Eelworm will be able to harbour, and if I gave out this as a 

 cure, people would be disappointed." * 



The report of my observer's later series of experiments, sent to me 

 during October, is as follows : — " I have now completed my experi- 

 ments for killing the Eelworm, Heterodera mdicicola, and, as promised, 

 now send you an account of them. In my first experiment, I used 

 pots that held four and a lialf pounds of infested soil, and to each pot 

 I used the following chemicals, at the rate of one, two, three, and four 

 grammes to each pot : — Magnesium sulphate, iron sulphate, tartaric 

 acid, lead acetate, citric acid, sodium sulphite, sodium hyposulphite, 

 sodium caustic, potassium sulphite, potassium permanganate, potas- 

 sium chloride, potassium ferrocyanide, potassium sulphide, potassium 

 sulphate, potassium caustic, potassium acetate, carbolic acid, and 

 potassium cyanide. Gas-lime (fresh) up to twenty grammes ; fresh 

 caustic lime up to twenty grammes ; tobacco powder up to eight 

 grammes. 



" The plants in the potassium ferrocyanide were all killed, even the 

 plant to which I only used one gramme to the four and a half pounds. 

 The plants in the gas-lime were sickly at twelve grammes ; but the 

 Eelworm was not even checked with twenty grammes. All the other 

 plants did well, and were not injured in the least. The only things 

 effectual in checking the Eelworm were carbolic acid and potassium 



* My observer requests me, for obvious reasons of business considerations and 

 also inconvenience in time taken up in reply to ajiplications regarding treatment, 

 not to insert his name and address ; but for scientific communication, he has 

 allowed me to put him in communication with Dr. J. Kitzema Bos, Professor at the 

 State Agricultural College, Wageningen, Netherlands, who aided ns in identification 

 of the Eelworms ; and also with Prof. Atkinson, of the Agricultural Experiment 

 Station, Auburn, Alabama, U.S.A. ; and with Dr. J. C. Neal, Director of the Agricul- 

 tural Experiment Station, Oklahoma, Ind. Tei'ritory, U.S.A., to whose published 

 researches on the Heterodera radicicola, or Root-knot Eelworm, all who study the 

 subject are infinitely indebted. I am therefore not without hope that the patience 

 and care with which the observations have been conducted over months of experi- 

 ments may produce more fruit than the observer is aware of, and (at least in 

 scientific quarters) will be credited to the right owner. — Ed. 



