Heter: 3 



There, aoparently, the normal proliferation which we get vrith nost of 

 the other species is not apparent. Also, in the leguminous plants 

 nodulation is suppressed. 



In looking at a field the first sign that the fanner gets that the 

 cyst nematodes are present is a stunting of the plants. In the case 

 of the sugar beet root, the main root or tap root is attacked and there 

 is a proliferation of lateral roots which in turn become studded with 

 the swollen and white female forms. In peas the main root may be some- 

 what thick and fleshy and one may be mislead by not seeing the nematodes 

 on the surface. However, upon dissecting the root large numbers of the 

 males and females which are imbedded in the roots may be easily found. 

 When the lateral roots which are smaller in diameter are inspected, the 

 female nematodes may be found shoi^ing at the roots' surface. One may 

 get heavy infestations of this type without root proliferation and loss 

 of the nodules. 



TRStroS: Egg sac development 



Within this nematode group there are certain fairly obvious trends, 

 for example, consider the egg sac. Let us start with the Meloidogyne. 

 In this genus there is a large egg sac and, if I am not mistaken, vir- 

 tually all of the eggs are extruded into it. I'Jhen we come to the Heter- 

 odera we find some that are not quite reminiscent of that, for example, 

 H. cruci ferae and H. carotae , in which the egg sac is quite large and 

 absolutely full of eggs. There may be fully half of the eggs produced 

 laid in these sacs. If one is lucky, he may see these eggs maturing and 

 the larvae hatching. This having eggs in an external sac is of some 

 importance in making larval counts, that is, encysted egg counts. The 

 next stage is found in H. gott i ngia na which has an intermediate size 

 egg sac containing a fair number of "eggs. Then we go on to types like 

 H. schachtii and H. cactii where only when the cyst is fairly mature and 

 well-filled with eggs are eggs laid in the sac. Next we come to forms 

 like H. humuli and H. aven ae which have a perfectly good egg sac, but 

 without eggs being pushed into it. It may be, although I am not sure, 

 that this is due to the fact that the vulva is too small for the eggs 

 to be pushed through. Now, at the end of the series we have H.^ rosto - 

 chien sis in which no egg sac is formed, although there may be a slight 

 trace~in earlier female stage. Certainly, in this case the vulva is 

 not large enough for the eggs to go through as is also true for H. major. 

 I, personally, believe that the egg sac is a constant feature of allT^f 

 the species, but that it is usually overlooked as it is sticky and may 

 adhere to the soil particles and so be lost, 



TRENDS; Response to root diffusate 



Another trend that one may distinguish is the response to root 

 fUffusates, I suppose that the response to root diffusates is a sort of 

 ultimate refinement to parasitism. The idea being the nematodes wait in 



