IDENTIFICATION OF EELWOEMS. 55 



female specimens of T. devastatrix found by himself in various kinds of 

 plants were placed in my hands by Dr. flitzema Bos, but as these 

 would not be of service to general investigators, I have not transcribed 

 them in detail, but refer the reader to his averages of these given at 

 p. 51. Proceeding further with his notes of measurement. Dr. liitzema 

 Bos added : — " Kuhn found in Dijisacus fullotium " (the Fuller's Teazle) 

 " T. devastatri.v varying between 0-94 and 1-162 mill. ; in Clover 

 between 1-21 and 1-56 mill. The Tulcnchi in the Hop-roots bad a 

 length of 0-76, 0-74, 0-94, 1-02, and O'GG mill. 



" The Tylenclii 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 Tijlenchus 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 larvfe, but 

 only a very small number of females. 



"It is also very curious that in the diseased Hop-plants should 

 exist both species, — T. devastatrix and H. schachtii. Though I agree 

 with you that probably the latter will prove to be the real cause of the 

 disease, only infection experiments can decide whether the first or the 

 second Nematode is the real cause. Perhaps one is the cause, and the 

 other increases the efiect of the disease." — (J. E. B.) 



In regard to identification of the long and narrow (in fact, eel- 

 shaped) Eelworms which I found in the white jxirt of the bark beneath 

 the bast, and which I found difficulty in difl'erentiating as to whether 

 they could certainly be described as of T. devastatrix, or larvfe and 

 males of H. schaditii, Dr. Ritzema Bos replied : — "I found also male 

 and larval Heterodera schachtii in the roots of the Hop, but more in the 

 little rootlets than in the thicker roots ; but there is a clear difference 

 between a Tylenchus and a larva or a male of H. schachtii, as you can 

 see by comparing the figure," &c., " of my ' Tierische Schadlinge und 

 Niitzlinge.' " 



For these figures, given in present Report by kind permission of 

 Dr. Ritzema Bos, the reader is referred to the plate of Tylenchus 

 devastatrix, and to the figures of H. schachtii at p. 5G. 



There it will be seen that the tail of the Tylenchus ends, as figured 

 on plate at 1 and 2 ; the tail of the male of H. schachtii (see figure of 

 male Eelworm, still encased, p. 56) is rounded at the end, and the 

 spicula are placed near the end of the body ; the termination of the 

 tail of larva of II. schachtii is also given accompanying in same figure. 

 Further (and see figures), Tylenchxis has a sucking-stomach and a 



