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he observed what he calls "club root" in violets in 1876. This 

 without much doubt was the work of nematode worms. The trouble 

 seems to have been common since about 1888, most articles on the 

 subject having appeared since that time. It is now common every- 

 where and known to every gardener and florist. 



Identity of our Species. 



We have carefully examined the work of Strubell, Neal, Atkinson, 

 and Cobb, and compared them with our own. Atkinson's excellent 

 account of the Alabama species leaves no doubt that it is identical 

 with ours. The only discrepancy of importance is in regard to the 

 structure of the male reproductive organ, to which we have already 

 referred in discussing the structure of the male. In all other 

 respects his description applies perfectly to what we have found. 

 That portion of Neal's work which relates to the structure and devel- 

 opment of the worm is by no means complete and contains not a 

 few obvious errors, but indicates nevertheless, without much doubt, 

 that his species was identical with Atkinson's and that which we 

 have investigated. Cobb, also, appears to have had the same 

 species to deal with in Australia. It may therefore be assumed that 

 the forms studied by Neal, Atkinson, Cobb, and ourselves, are all to 

 be referred to the species which has been called Heterodera radicola, 

 (Greef) Miill. 



An examination of Strubell's very complete and accurate descrip- 

 tion of Heterodera Schachtii shows that our species^ if not identical 

 with that, is hardly more than a variety of it. The identity or dis- 

 tinctness of these species has always been unsettled. The only 

 really distinctive character between the two of which we have been 

 able to find any statement is that of Atkinson in regard to the male 

 testis, and of which, as already stated, we doubt the validity. Aside 

 from this we find nothing which could not be considered as individ- 

 ual variation or at most a difference of variety. We were able to 

 examine a few mature females of H. Schachtii brought by Dr. Stone 

 from the Experiment Station at Halle, and found them apparently 

 identical in structure with our H. radicola, but we were not able to 

 compare the two in all stages of development. It would seem 

 remarkable that forms should exist agreeing so completely in general 

 structure and in the details of so unique a course of development 



I 



