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Plate X. illustrates the result of one experiment which bears upon 

 this point. The photograph was taken in our experiment house and 

 shows six pots with dead immature cucumber plants in them which 

 were set out at the same time as the other robust uninfected plants 

 shown at their right and left. In this experiment two of the pots 

 received before planting 30 cc. of Carbon bisulfid each ; two also 

 received 30 cc. of Ammonia water from gas works ; and two pots 

 were treated with 2 100 cc. of Potassium permanganate at the rate 

 of r-300. The Potassium permanganate pots were again treated 

 twice some days afterwards with the same amount and strength of 

 solution except that the last treatment was at the rate of 1-250. 

 Microscopic examinations of the soil after treatment showed many 

 dead worms, but ten days afterwards when the young cucumbers had 

 already appeared, an examination of the soil showed abundant 

 nematodes, and galls had commenced to form profusely upon the 

 roots. The cucumbers in each of the six pots were in badly infested 

 earth and none of them ever lived to be more than 15 inches in height, 

 and notwithstanding the fact that each pair of pots received differ- 

 ent treatments of a severe nature there was no choice between the 

 plants a few weeks later. Such results as these demonstrate the 

 futility of attempting to treat nematodes by chemicals, for here we 

 had them confined to pots, or in other words to narrow limits and 

 under the most favorable conditions for exterminating them. Even 

 should this treatment have proved successful the amount of sol- 

 ution which would have to be applied to open soil on a large scale 

 would be costly. Almost all solutions when applied to the soil in 

 considerable quantities are harmful to the plants. Potassium per- 

 manganate appears not to injure plants as much as one would sup- 

 pose. We have applied at a single time 2500 cc. (over two quarts) 

 of this solution at the rate of 1-250 to a 10 inch pot of earth con- 

 taining cucumbers, without the slightest ill effect. Ammonia water 

 from gas works as we obtained it is injurious when applied even at 

 the rate of 1-6 ; that is one part of Ammonia water and six parts of 

 ordinary water. Potassium sulfid is more injurious to plants than 

 Potassium permanganate and a mixture of Sugar and Lime even when 

 considerably reduced is quite injurious; although Lime itself causes 

 no harm to cucumber plants and is sometimes used by practical 

 growers to improve their soil. Carbon bisulfid was applied to the 

 soil usually before the plants were set out. This was done as fol- 



