100 CORN AND GRASS. 



a "cluck-necked" Onion. This swelled stem is usually 

 surrounded by a number of small doubled-up shoots, pale 

 in colour, and bent to and fro, instead of being properly 

 extended. The figure (p. 99) shows the appearance of an 

 attacked plant as it is often seen ; the disease is also known 

 as " Segging," or " Sedging," from the Sedge-like appear- 

 ance often assumed by the leaves. From the healthy growth 

 of the plant being checked there is necessarily much loss both 

 in straw and grain. 



This disease has been much noticed of late years, especially 

 in Scotland; and on investigation in 1886 I found Eelworms 

 present in the bulb-like base of the stems, as well as in the 

 spongy curled shoots ; and from the resemblance of the 

 diseased Oat-plants to the diseased appearance which is 

 assumed by Eye when attacked by the Eelworm known by 

 the name of TylencJms dcvastatrix, it appeared likely that this 

 Eelworm was also the cause of our attack ; and on special 

 investigation being made at my request, by Dr. J. G. do Man, 

 of Middleburg, and Dr. J. Eitzema Bos, Professor of Zoology 

 at the State Agricultural College, Wageningen, Holland (both 

 well known for their minute and skilled research into the 

 history of Nematode worms), this proved to be the case. 



On examination of Oat-plants badly affected by " Tulip- 

 root," or Segging, which I forwarded to Dr. de Man for his 

 inspection, he wrote me that he found inside the lowest part 

 of the stem a large quantity of living specimens of Tylenckus 

 derastatrix, and a few days later, when he had examined more 

 of the diseased plants, he further wrote that he had found in 

 all of them large quantities of living specimens of this Eel- 

 worm. 



Dr. J. Eitzema Bos also considered the above to be very 

 characteristic specimens of the peculiar diseased growth 

 under consideration, and on examination he found in them 

 " a large number of Tijlenchus dcvastatrix, males and females, 

 larvpe and eggs." 



Frequent examinations and careful study each season have 

 confirmed these observations fully, as well as shown that this 

 is one of the attacks which may with a little care be very 

 much lessened or entirely prevented. Descriptions and mag- 

 nified figures of the Eelworms will be found under the head 

 of ' Clover- stem Sickness ' ; and in my ' Eeport on Injurious In- 

 sects ' for 1889, fuller details are given, together with a full-page 

 illustration of these Eelworms highly magnified, copied by kind 

 permission from original drawings by Dr. J. Eitzema Bos.* 



* For full information as to the habits of this Eelworm, plants infested by 

 it, description, measurements, and excellent figures, in fact complete details, 

 see ' L'Anguillule de la Tige,' par Dr. J. Eitzema Bos, Haarlem, 1888, and 

 Part 2, 1889. 



