Rothamsted Experimental Station, Harpenden, Herts, England.
Present address: * National Cereals Research Institute, Private Mail Bag 5042, Moor Plantation, Ibadan, Nigeria.
No one fixative out of F. 4%, F.P.4: 1, F.A. 4: 1, F.A. 4: 10, T.A.F. and F.A.A gave the best definition of all morphological features examined in Pratyenchus brachyurus (Godfrey, 1929) Filipjev & Schuurmans Stekhoven, 1941 and P. zeae Grrham, 1951, but results with F. 4% and F.P. 4: 1 were most satisfactory. Nematodes stored in plain fixative deteriorated less than those stored in glycerol following processing by Seinhorst's technique. Specimens fixed in T.A.F. and stored in glycerol became transparent but those fixed in F.P. 4: 1 before processing retained their features best. All fixatives caused changes in dimensions but F.4% and F.P.4:1 affected them least. Seinhorst's technique caused more shrinkage but preserved morphological features better than Baker's technique.
