MeloirlsE 



larval development quickly, reaches the adult stage apparently wi thout 

 feeding and without any appreciable change in size, occurs in other 

 groups of the Tylenchoidea, Tylenchidea , Tyl en china , or whatever you 

 wish to call it, for it is the typical Allantonematoid life cycle. 



V/e do not yet know much about the life cycle of the new genera, Meloid - 

 odera , Trophotylenchulus , and Trophonema . It looks as though their life 

 cycle might be similar to that foi.md in Tylenchulus . I think the life 

 cycle in Nacobbus is different. 



With those generalities over, I am going to go on from here and recount 

 some of my own observations and experiences in working with this group 

 and make a few suggestions as to what may perhaps be the reasons for 

 this behavior. In so doing, I am making them merely as s-uggestions, 

 with no insistence that they are correct. I expect a good place to 

 start is with the egg. 



The egg of the root-knot nematodes does not have delayed hatching in 

 the sense that is found in the genus Heterodera . Eggs of the root- 

 knot nematode are said to hatch at maturity, providing consitions are 

 favorable. The question then arises, "What are favorable conditions?" 

 or perhaps one should say, "What are the unfavorable conditions that 

 might retard hatching?" One condition that may retard hatching is 

 drought — dry conditions, lack of moisture, 



I remember when Oliveira was spending a summer in Vfeshington. She 

 demonstrated to me the method they were using in Hawaii for obtaining 

 root-knot larvae for experimental work. She went out, or sent someone 

 out, into the fields in the area of Washington and got her material, 

 infested plants. They were field grown. She brought them, into the 

 laboratory, put them in a suitable container with a small amount of 

 water, sloshed them around, and soaked them awhile. Then she poured 

 off that water into a filter paper and set ud her apparatus. It was a 

 modified Baerraann funnel. 



It was Friday afternoon when she was demonstrating this to me, and she 

 brought it to me the next Monday morning. She had what looked like a 

 half thimble full of root-knot nematode larT/-ae, absolutely free from 

 debris and practically free from other kinds of nematodes. I was very 

 much impressed. I had been hatching larvae and doing all right, but 

 viith a good deal more work. Therefore, I forthwith did as she had. 

 There were about twenty populations of root-knot nematodes growing in 

 the greenhouse at that time. I got my material and set it up as she 

 had. 



The next morning I had nothing. At first I thought perhaps iliss Olivera 

 had been so in contact with the mystic Orient that she had developed 

 some magic touch in her fair hands, but I thought that was no way for a 

 scientist to think. The explanation ivas, or what I feel confident it 

 was, is that she had got field material in v;hich eg";s had accmulatod. 

 The larvae had matured but had failed to hatch, ^30 that in h.^r material 



