MeloJdrB 



I am suggesting chat the reason the fenales developed in those 

 nitrogen nodules is that the tissue of those structures was of such a 

 nature that the nematodes could feed on it, while, perhaps, they could 

 not feed on the other parts of the root system. 



There has been great speculation on why it is that an occasional root- 

 knot nematode will develop on a resistant plant. T5very now and then 

 some are found that will, for one reason or another, come through and 

 lay a few eggs. It has been suggestnd that if one could just gather 

 those eggs, rear them, then put them on the same plant again, and maybe 

 get a few more that layed a few eggs, that in a little while one could 

 probably breed a strain of root-knot nematodes that would not be sus- 

 ceptible to this particular plant's selective elimination proposition. 



I suggest that the reason those individuals happened to grow up and lay 

 a few eggs was due entirely to their postion on the plant. They were 

 lucky enough to get somewhere on the roots where there was a little 

 plant tissue that retained enough protoplasm in the cells that they were 

 able to feed on and get enough food to reach matvirity. It was only 

 those lucky ones that happeded to get in such positions that were able 

 l.o mature. 



Just one more comment or observation before closing. Quite a nimber of 

 years ago, when I was working with Dr. Amdt at Clemson, we were inter- 

 ested in the possible role of nematodes in certain cotton seedling dis- 

 eases. We were interested in their possible connection with the diseases 

 of "sore shin" and "big shank." The latter was a condition in some of 

 the fields in South Carolina in which the hypocotyls were enlarged. The 

 two disease symptoms did not look alike. In the case of big shank there 

 were no lesions. 



I took quite a number of plants from fields showing big shank back to 

 the laboratory at Clemson, and I teased them out with needles. I could 

 find nothing. There were no nematodes in them that I could recognize, 

 although I looked vjith considerable care. At that time the problem 

 rested there. 



Then some years later I had occasion to grow cotton seedlings in root- 

 knot infested soil at Beltsville. Everyone of them developed big shanlc. 

 That put me to thinking, so I really went after it that time. Vie cut 

 and studied sections and easily found the remnants of females that had 

 gone in and lived long enough to cause the swelling but had finally died. 

 They were no longer living, I am sure, when we teased them out, but they 

 were still there. They are not easy to find, but one can find them by 

 sectioning. 



That reminded me of some carrots that came to the laboratory at Belts- 

 ville. They had beautiful root-knot on them. Of course, everybody 

 knows that carrots are very susceptible to root-knot, and everybody 

 knew exactly what was on them when they were questioned about it. Some- 

 body just suggested in sort of an off-handed way that one of the girls 



