27 



and yet be distinct species. Certain violet roots sent in for examin- 

 ation by a gardener in this state were found to be infested with a 

 nematode agreeing in every way with the ordinary H. radicola which 

 we were investigating, except tliat the eggs, one of which is shown 

 in plate IX., fig. 6, were only three-fourths as large. The structure of 

 the worm was the same in every particular, the embryological devel- 

 opment was similar, yet every egg of the thousands in the lot had 

 the unusually small size. Shall this be considered a distinct species ? 

 If not, then we can see no reason for considering Heterodera radi- 

 cola as a distinct species from H. Schachtii, until actual comparison 

 shall show them to be so, on characters not yet established. 



Note. — Since the above was written there has appeared a bulletin on the cotton plant 

 from the Office of Experiment Stations, U. S. Department of Agriculture, in which, under 

 the heading- of diseases of the cotton plant Professor Atkinson has briefly described the 

 nematode root gall disease. In describing the structure of the male worm he speaks as fol- 

 lows : " Occasionally some males were found which showed but a single testis. Since 

 Heterodera Schachtii possesses but a single testis, it might be well to inquire whether that 

 species was also present and whether they are associated in the same roots in some cases or 

 whether there is a variation in H. radicola in the possession of paired and single testes.'' 



This statement has a very important bearing on the question as to the relations between 

 H. Schachtii and H. radicola in that it casts a doubt upon the only distinctive feature 

 between the species which has been presented. If the first hypothesis be true ; namely that 

 both species are present in this country as distinct species, then it would be natural to con- 

 clude that our species is H. Schachtii while that studied by Atkinson in Alabama in 18S3 

 was H. radicola. The almost absolute agreement of our results in detail, however, leaves 

 but little doubt that we had the same species to deal with. If the second hypothesis, that 

 "there is a variation in H. radicola in the possession of paired and single testes," be correct, 

 then the separation of the species on this character loses its value completely. We feel, 

 therefore, all the more certain that Heterodera Schachtii and Heterodera radicola are one 

 and the same species. 



