OBSERVATIONS IN KENT. 53 



Being desirous to know more on the subject, I applied to Mr. E. 

 A. White (mentioned below), with whom I had previously been in 

 correspondence on other subjects connected with Hops, who put me in 

 communication with Prof. Percival, with the remark added, "He was 

 the first through myself to discover the troubles, of which there are 

 two in the roots." — (E. A. W.) 



On Sept. 9th, Prof. Percival was good enough to write to me 

 that, in reference to the disease known as " nettle-headed " Hops, he 

 had been paying attention to it for some time, and found it was 

 caused by a lleterodera, which he considered to be H. schachtii, and 

 that along with this Nematode there was almost always to be met 

 with in the thick parts of the roots Tylenclms devastatrix. "With 

 regard to this species, Prof. Percival mentioned he thought there 

 could be no doubt, also that it had been carefully examined by Dr. De 

 Man, who had also verified his identification of H. schachtii. (Dr. De 

 Man being a well-known observer and writer on Nematode-worms, his 

 opinion is very valuable in this interesting investigation. — Ed.) 



A little later on. Prof. Percival was good enough to send me a 

 little box of Hop-rootlets in earth, which gave me a good supply of 

 the H. schachtii in various stages for microscopic examination, some of 

 the citron-shaped females of which I give a figure of mngnified (as I 

 observed tliem, outside the Hop-rootlets) at 4 and 5, p. 56. 



With rec/ard to the other kind of Eelworm found present, which appears 

 in all essential points not to differ from our only too common " Stem 

 Eelworm," found in "Tulip-root" disease and " Stem-sick " Clover, 

 namely, the Tylenchxis devastatrix, Prof. Percival wrote me on Sept. 

 IGth: — "Some Hop-roots were sent to me a day or two ago, and 

 some this morning ; the thick parts I am sending herewith contain 



and topples over ; when not tied up the whole stem becomes slack, slides down its 

 support, and the plant lies in a heap on the ground. So far the experiments which 

 are being carried out on the Beltring estate of Messrs. E. A. White and Co., 

 Paddock Wood, point to the circulation within the plant of a poison which brings 

 about curling of the leaf, stoppage of growth of the fibro-vascular tissue, and loss 

 of turgo of the cells in the leaf near the ribs, with resulting yellow jjatches there. 

 The leaves on the main stem nearest the ground are affected first, and then follow 

 those at the nodes above in regular succession. The branches in the axils of these 

 show the same regular sequence of diseased leaves, the lower branches being 

 affected first. The cause is undoubtedly connected with the root, and Professor 

 Percival finds in the cortex of many diseased specimens, close up to the bast, con- 

 siderable numbers of the Nematode Tylenchus devastatrix, Kuhn, usually known as 

 an Eelworm. Before any completely satisfactory cause can be established or 

 remedy suggested much work is necessary. At a later date we hope to be able to 

 give an extensive communication from Professor Percival dealing with this inter- 

 esting and important investigation. — 'Natural Science' for Sept," From 'London 

 Corn Circular,' No. 71, p. 14, 1894. 



