Comparative Relationship between Meloidogyne chitwoodi and M. hapla population Densities and Growth of Sugarbeet Seedlings.

ever, this may merely be a reflection of the extent to which the cuticle has been reabsorbed at the t ime of fixation since the cuticles of all these Lts are part ial ly reabsorbed dur ing moult ing. Also, the cuticle of the L~ of O. phyllobia appears to be structurally more complex than that of A. agrostis since it has a distinct striated basal layer (Fig. 1A, D) which is reabsorbed at a later stage so that the cuticle which surrounds the second-stage larva (L.,) consists mostly of epicuticle (Fig. 1B, C, E). T h e life of the Lx cuticle is short in all the nematodes ment ioned above, and it is possible that striations in the basal layer may have been present for a brief period prior to their reabsorpt ion in A. agrostis, al though they were never observed. I t is clear from our observations that O. phyIlobia does moul t once in its egg; therefore, the larva that emerges on hatching is all L2. Orrina phyllobia: Bird, Orr 409