EEL WORMS. 
107 
In the dead part of the stubble from Arniston mains only a few 
Tylenchus devastatrix were present, it being a habit of these Eelworms 
(as far as has been observed in Rye) to leave the dying plant; but Dr. 
Ritzema Bos “ found this species in somewhat greater numbers in the 
young shoots that were springing from the haulm of the Oat stubble, 
which were still alive and green. All these were without doubt Tylenchus 
devastatrixT Other Anguillulidae, or Eelworms, were present in the 
dead part of the plants, or in the earth hanging about them, belonging 
to the genera Diplogaster, Cephcdobus, Rhabditis, Mononchus, Plectus, 
and Dorylaimns, of which Dr. J. R. Bos observes that “ all these live 
in humus or in earth, and are not plant parasites, and cannot possibly 
be the cause of Tulip-root disease.” » 
Further I may add that early in the correspondence I forwarded a 
few plants remaining to me of specimens of last season’s Tulip-root, 
then quite dried up, to Dr. J. G. de Man, who was so good as to 
examine them, and pronounced that he found specimens therein of 
Tylenchus, which he considered to be Tijlenchus devastatrix, Kuhn, but 
these being dead, and not sexually developed, he could not speak with 
absolute certainty of the species; but Jater, in a few specimens of 
Tulip-root from the same packet, above alluded to (from field mentioned 
at p. 42), Dr. de Man found a perfectly developed male of the Tylenchus 
devastatrix, Kuhn. From the fact of this species of Eelworm being 
found in our English “Tulip-rooted” Oat plant, as well as in the 
German similarly diseased plants, there is now no reason to doubt that 
this, namely, the Tylenchus devastatrix, Kuhn, is the cause of the 
attack. 
The T. devastatrix is considered to be the only species of Eelworm 
that causes Tulip-root,* but many other kinds are often ^present, either 
in or amongst the sheathing-leaves or the roots of the Oat plants. As 
it is impossible for any but those who have long and minutely studied 
the subject, and also are aided by strong microscopic power, to deter¬ 
mine the differences between these kinds correctly, I do not give the 
descriptions; but having been so greatly favoured by-Dr. de Man as 
to receive from him a list of the different species which he found 
present, in or accompanying the Oat plants I forwarded to him, I, with 
his kind permission, give this information, as it will be of much interest 
to students of the subject before passing on to iheans of prevention of 
Tulip-root. Dr. de Man wrote to me :—“ I have found Cephalobus 
rigidus, Schneider, which is identical with Cephalobus oxyuris, Biitsche, 
* For description and figure of the Tylenchus devastatrix, by Dr. Kuhn, see 
‘ Zeitschrift fiir wissenschaftliche Zoologie,’ T. ix., p. 129, plate vii. c. Likewise, 
by the same author, ‘ Die krankheiten der Kulturgewachse,’ Berlin, 1858, p. 179, 
and plate v. It is also described in Dr. H. Charlton Bastian’s “ Monograph of the 
Anguillulidee,” vol. xxv. of the ‘ Trans, of Linnean Soc.,’ p. 128. 
