EELWORMS. 



215 



so appropriately applied to the effects of an infestation 

 on any crop that it thoroughly describes its appear- 

 ance, and at the same time is not applicable to any 

 other kind, it is very desirable that this name should 

 be used. And in the case of Eelworm presence, where 

 the •wormlets are so small that it requires powerful 



G. 158. — 1, J'l/lenchvs ohtusn.'i ; 2, Aphelenchux avencc ; 3, Plectus 

 obtus2i!i, of Bastian (all enormously magnified).* 



magnifiers to see them at all, it is very important to 

 be able to tell by some well-defined external sign what 

 kind of internal infestation is causing the mischief. 



The Tylcnclws derastatrix is chiefly hurtful, in this 

 country, to Oat and Clover jDlants. The wormlets (see 

 Fig. 15G, p. 213) are excessively minute white worms ; 

 at their full growth they are not more than a])out 

 one twenty-fifth part of an inch in length, and of an 



* The three species oi Eehvorms represented above are copied from 

 the figures by Dr. H. Charlton Bastian, F.E.S., *c., given in Plate X. 

 of his " Monograph on the Av(juiUulidic,'' published in vol. xxv. of 

 the ' Transactions ' of the Linnean Society. 



