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NATURE OF THE SOIL AS EFFECTING NEMATODES. 



Some observers' have maintained that when artificial soils such 

 as coal ashes mixed with peat were used, nematode galls were not 

 formed except in the small ball of earth clinging to the plants when 

 transplanted. It might be supposed that a soil of the nature of coal 

 ashes would not constitute a favorable medium for nematodes and 

 we have never observed any galls on plants in this medium, although 

 we have obtained them abundantly on roots cultivated in peat soil 

 and also to a certain extent in sawdust cultures. A single experi- 

 ment made with a lo in. pot of peat containing cucumbers will suf- 

 fice to show that nematodes will thrive in a strong acid soil such as 

 peat. About a thimblefull of nematode infested earth was inserted 

 I in. beneath the soil close to the plant. Six weeks later the plant 

 was taken up and examined and there were more than one hundred 

 galls upon the roots. Cucumbers were again planted in the pot and 

 their roots likewise became covered with galls. Nematodes in all 

 probability can thrive to a limited extent in every soil in which their 

 host plant is capable of flourishing, although there are certain soils 

 such as coal ashes which do not appear to be especially adapted to 

 their development and growth. 



INFLUENCE OF CARBON-DIOXID AND OXYGEN. 



All animals require Oxygen although not in the same degree. 

 The fact that nematodes live in the soil which is richer in Carbon- 

 dioxid than the air would indicate that they are normally adapted 

 to a larger percentage of this gas than ordinary animals, and since 

 they thrive in decomposing manure heaps they must be subject to a 

 great variety of gases and chemical solutions of a strong nature. 

 We observed, however, that when nematodes were placed in an 

 atmosphere containing 85% of Carbon-dioxid their movements 

 largely ceased in a very few minutes, but as soon as air was supplied, 

 they resumed their movements. 



I. See experiments of E. H. Jenkins and W. E. Britton in Conn. Agrl. Expt. Station 

 Report, 1S95, P- 92- 



