STEM EELWORM ; ROOT-KNOT KELWORM; I3EKT EKLWORM. 49 



These Cockle-galls are easily observable ; but with regard to the 

 Eelworms which have to be searched for scattered in infested stems or 

 roots, or in the earth round the rootlets, the case is different, and a 

 very large proportion of us have to judge whether they are at work by 

 the peculiar distortions of growth or formation of galls given rise to by 

 the infestation. Also when we have captured the Nematodes and got 

 them fairly on to the microscope slide, there are similarities which 

 make certain identification sometimes so very difficult, that possibly it 

 may be of more use to give notes of the Eel worm infestations mentioned 

 at the heading with their distinguishing characteristics together (for 

 convenience of comparison), rather than to disperse them under the 

 headings of the names of the crops which they may have been more 

 especially attacking. 



Firsthj, just to note the main distinctions of the three most important 

 kinds of Eelworm noted at heading, the Stem Eelworm, Tijlenchus 

 derastatri^', vihich. we knov/ best as causing "Tulip-root" in Oat plants, 

 and " Stem-sickness" in Clover, is ahcaijs eel-shaped ; reference to the 

 figures at p. 47, and in the plate, will show that the little eel-like form 

 is to be seen in the egg, and in the young or larval state it is also eel- 

 like, and so are the males and females. 



With the "Root-knot" Eelworm, '' Hcterodera radicicola," which 

 does injury most especially by causing gall-growths at the roots of 

 various plants, the development is different. The young Eelworm may 

 be seen (see fig., p. 01) in eel-like shape in the egg, and it hatches out 

 like a little eel, and after wandering for a time forms a kind of cyst, 

 from which the male comes out in eel-like shape. But it is not so with 

 the female. In her case the body swells up into a gourd-like or pear- 

 shape, and gradually becomes filled with eggs and young larvte. As 

 yet this species of Eelworm, though present on the Continent, and 

 very injurious in America, is little known in this country, excepting as 

 damaging some kinds of crops under glass, and especially Tomatoes 

 and Cucumbers, by causing gall-growth at the roots. 



The Beet Eelworm, Ileterodera schachtii, is very like the Root-knot 

 Eelworm ; it is eel-shaped both in larval and developed male condition, 

 and the female is not eel-shaped but swelled, but it differs from the 

 female of H. radicicola (the Root-knot Eelworm) in being citron- or 

 lemon-shaped (see fig., p. 5G); the habits of these two species difler in this 

 respect, that though both of the kinds are to be found in the roots, and 

 in the earth round the roots of the plants which they infest, yet the Beet 

 Eelworm does not apparently cause gall-growth. This kind of Eelworm 

 is especially injurious to Beet on the Continent of Europe, and, as will 

 be seen further on, has been observed in the past season at one locality 

 in England at the roots of Hops. 



The distinctions above mentioned, namely, that the females of the 



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