ROOT-KNOT EELWOKM. 133 



infer that, in this manner, they obtain entrance in young rootlets." 

 Once within they can make their way about in the tissues of the root, 

 and the result of their presence is the unnatural development of cells, 

 producing the irregular growth known as the gall or root-knot. 



The variety both in form and locality of the galls on the roots, and 

 in effect of the infestation to different kinds or classes of plants, 

 especially to field vegetables, and to fruit trees, are clearly and service- 

 ably detailed by Dr. Neal. Of these I quote the following paragraph 

 as most applicable to our own circumstances : — " The roots of the 

 Okra, Eadish, Turnip, Cabbage, Cucumber, Melon, Cow-Pea, Peanut, 

 Tomato, and Egg-plant enlarge enormously, soon becoming little else 

 than masses of decaying tissues. The plant stops growth, the fruit 

 either becomes distorted, or drops prematurely, the leaves change 

 colour and fall oft", and the plants die so rapidly as to justify the usual 

 expression ' struck by lightning,' applied to the fields of Melons, 

 Cucumbers, Tomatoes, and Cow-Peas, so often badly affected by the 

 root-knot " (J. C. N.). This rapid and sweeping effect, it should be 

 observed, is an account of damage in U. S. A. ; circumstances, where 

 climate permits Melons and Tomatoes to be grown in the open air 

 in fields, put this Eelworm attack on a very different footing to what it 

 is here. In some other attacks the enlargements caused by the root- 

 knot are chiefly on the main stem, near the surface of the ground ; in 

 others, as in nurseries of young Peach, Orange, or English Walnut 

 sown for stocks, when the trees have failed from infestation, the cause 

 is found " in the knotty decaying roots, without rootlets, or fibrillge " ; 

 and as observed by Dr. Neal in a few words of summary of this part of 

 his report : — " In all of these cases the effect is to deprive the stems 

 and leaves of the food and moisture ; the knots grow, the branches do 

 not."— (J. C. N.) 



The kinds of soil favourable for growth of Root-knot, appear to be 

 those which unite lightness and dampness. Thus the wormlets can 

 travel with the most convenience to themselves when on their way 

 through the earth to a new settlement, and they have also the 

 moisture which is favourable to their vigorous growth. It is stated 

 that " localities highly fertilized with composts, stable manure, or 

 leaf-mould, show the root-knot quicker in plants, than in compact or 

 virgin soils, and the worst results are found in gardens planted in long 

 cultivated, fully fertilized, and thoroughly pulverized areas." . . . 

 "A dry soil with solid growth is" — "unfavourable, hence, in many 

 locations, drainage has entirely changed the character of the land, so 

 that Peaches and Figs grow where they would not before." 



Infestation spreads rapidly from galled roots. Amongst various 

 instances showing this is a case where, " In a spot of new and non- 

 infested ground, several trees, Peach and Fig, were planted. The 



