Het-:r: 2 



to occur, for example, H. trifolii. One presumes that reoroduction is 

 parthenogenic in such cases. In other species, as for example H. schachti i 

 and H. rostochiensis , evidence is novr accumulating;, slowly it is true, 

 that the male is required. There is a recent note by Fassuliotis to the 

 effect that he. had raised ten isolated individual H. rostochiensis fe- 

 males and these were unable to oroduce eggs in the absence of males. 

 T^.llenby in England has made similar observations, as yet unpublished. 

 V/illiams in England has made studies using potato slices for cultures. 

 The slices are first surface sterilized and can then be inoculated with 

 suspensions of eggs or xjith individual nematodes, which can become es- 

 tablished quite well. Williams put a hundred single larval nematodes on 

 separate potato slices and obtained only two females which did produce 

 eggs. It is interesting to note that in the other females vrhich did not 

 produce eggs, there was a vestige of an egg sac. After fertilization, 

 ovulation begins and there is a gradual filling of the body with eggs. 

 The larvae develop and molt once to reach the second larval stage. Dev- 

 elopment is usually arrested at the second larval form. 



I don't think we know too much about the browning of the cyst. It 

 is said to be akin to the browning and hardening of insect cuticles. It 

 is my general observation that the brownin,^ doesn't actually begin until 

 the death of the female, that is, the really pronounced browninr; and hard- 

 ening due to the presence of polyphenol oxidases ?nd so forth. In H. 

 rostoch iensi s I don't believe that the earlier golden color and condition 

 is the same as the later hardening and browning of the cyst. One also 

 sees an intermediate yellow color in such cysts as H. trifo lii and H. 

 galle op sis . This is an intermediate creamy color as compared to the 

 golden color of H. rostochiensis . Species like H. scha chtii and H. got - 

 tingiana remain white and translucent until death then the "browning 

 occurs. 



PATHOLOGY 



Let us now turn to the subject of feeding. I don't need to say much 

 about this because Dr. Christie has dealt with it fully. The position is 

 almost like that in the MeloLd^ogyrie and giant cells are formed but, by 

 and large, there is almost no hypertrophy. In the case of K. sc hachtii 

 in young roots there may be a slight swelling in the vicinity of the 

 head, but this appears to be due almost exclusively to the presence of 

 the giant cells. There is no real hypertrophy, such as you get with the 

 Feloidogyne . There is a little bit more hypertroohy in some hosts, for 

 example, in tomato attacked by H. rostochiensis. In this case it would 

 be possible to mistake the presence of the"cyst nematode for that of the 

 root-knot nematode, although close examination would reveal the difference. 



The gross effect of feeding is usually to produce a proliferation 

 of the root system. This is true of all of the species except the pea 

 root eelworm and, ar; I learned yesti^rday, the soybean cyst nematode. 



