100 TOMATO. 



in my hands, but also from the scientific details and correspondence on 

 the subject, with which I was favoured by Dr. J. Eitzema Bos, Professor 

 at the Royal Agricultural College, Wageningen, Netherlands, and also 

 from the published information given by Dr. Neal, now Director of the 

 Agricultural Experiment Station, Oklahoma, Ind. Territory, U.S.A., 

 and more especially (duly acknowledged, as in the other cases) from 

 the minute and carefully recorded observations of Prof. Geo. F. Atkin- 

 son, Professor of Biology at the Agricultural Experiment Station, 

 Auburn, Alabama, U.S.A.* ; but a few lines of the latter are repeated 

 now to save trouble in reference, regarding some of the main charac- 

 teristics, and especially those by which this " Eoot-knot " Eelworm 

 is clearly distinguishable from the " Stem Eelworm," the Tylenchus 

 devastatrix, known as caushig Tulip-root, or Segging, in Oat plants, and 

 Stem-sickness in Clover. 



The eggs of the Root-knot Eelworm (see magnified figures, p. 99) 

 are stated to be, when mature, about three- to four-thousandth of an 

 inch in length, and the young wormlet, or larva, when it comes out of 

 the egg, to be from twelve- to sixteen-thousandth part of an inch in 

 length, and, like the adult male, it is thread-like in shape, and also, like 

 it, has at the anterior extremity, in the opening of the gullet, a fine 

 point on a trilobed base, known as the " exsei'tile spear." 



The life-history is, that the young wormlets wander about for a 

 time, then presently come to rest in the plant tissues, and undergo a 

 change. The body of the larva, or wormlet, is stated to enlarge, 

 excepting at the two ends, and forms a kind of " cyst," or chamber, in 

 which the change of the Eelworm to the adult state takes place. If 

 this is to the male condition, the wormlet in its chamber is stated to 

 lengthen and become more slender and thread-like, until it is curled 

 round several times within the chamber formed of its old larval skin ; 

 and when the change is complete, it breaks forth, roams in search of 

 its very differently shaped mate, pairs, and dies. Its measure when 

 full-grown is stated to be about one millimetre (the twenty-fifth of an 

 inch) in length, and only the seventeen-thousandth of an inch at the 

 middle, tapering to about half this width at the extremity at the head 

 end, in which the oesophagus, or gullet, is placed, which is furnished 

 at the foremost end with a minute needle-like point, which can be 

 thrust out and retracted, and rests on a trilobed base. It will thus be 

 observed that these male Root-knot Eelworms, from the time they quit 

 the egg up to the perfectly developed condition, preserve the same 

 thread-like, or fine eel-like, shape. 



* ' A Prelimiuary Report upon the Life-history and Metamorphoses of a Eoot- 

 gall Nematode, Heterodera radicicola (Greef.), MulL, and the Injuries caused by it 

 upon the roots of various plants,' by Geo. F. Atkinson. Science Contributions from 

 the Agricultural Experiment Station, Alabama, U.S.A., Dec, 1889. 



