STEM EELWOEMS. 



27 



given, amongst other points entered on, of various applications found 

 successful at Eothamsted in checking Eelwcrm Clover-sickness and 

 pushing on good growth. 



In the Fourteenth Beport, special account of this attack as affecting 

 Field Beans, with identification by Dr. Eitzema Bos of T. dcvastatrix 

 as the cause of the stunted and deformed growth, and life-size figure 

 of one of the attacked plants. 



In the Eighteenth Report, the discovery by Prof. J. Percival (of the 

 South-Eastern College, Wye, Kent) of presence of Eelworms showing 

 no apparent specific distinction between them and T. devastatrix, and 

 found by him in Hop roots, is mentioned. This is a matter of much 

 scientific interest relatively to the position of the wormlets being not 

 in the stem or buds, or modifications of those parts, but in the roots. 

 Regarding this infestation Dr. Eitzema Bos, to whom specimens were 

 submitted, observed : — 



" I found in the larger parts of the roots which Prof. Percival sent 

 me, in the cortex close to the bast, Nematoid worms closely allied to, 

 if not identical with, Tylenchus devastatrix. I never found T. devastatrix 

 in roots, always in stems and leaves (also in subterranean caulomata 

 and phyllomata). . . . The Tylenchus in Hunmlus roots is some- 

 what smaller than T. devastatrix, but as this species varies much in 

 length, that would be no cause why it should not be devastatrix. . . . 

 The Tylenchi in the Hop roots are smaller than the T. devastatrix in 

 other plants, but the maximal length of those of Hop roots surpasses 

 the minimum length of Dipsacus (according to Kuhn : I myself never 

 found so small ones), and as I cannot find any other constant difference 

 between the Hop-root Tylenchus and T. devastatrix, we may say that 

 the Hop-root Tylenchus must indeed belong to this species. It is the 

 first time that I find T. devastatrix in the roots ; I always found it in 

 the stems and the leaves only. It is curious that I found in the Hop 

 roots a very large number of males, also larvae, but only a very small 

 number of females." — (J. R. B.) 



Other observations on the subject by Dr. Eitzema Bos, and com- 

 munications with which I was also favoured by Prof. Percival, will be 

 found in the same paper. 



In the Tiventieth Report, detailed observations will be found — 

 pp. 107-115 — on the misshapen swelled and cracked growth of 

 Onions, caused by infestation of T. devastatrix, or Stem Eelworm. 

 This " Eelworm- sickness " has been known for about twelve or more 

 years as injurious to Onions in Holland, but has not been reported as 

 present in this country until 1896, in which year full observation of 

 the characteristics of the damaged bulbs and swelling of the flag or 

 leaf above the bulb were sent me, and I also found the attack present, 

 so as to be able to study it, in my own garden. 



