Let V∕k be an irreducible affine
algebraic variety of dimension ≧ 3 defined over an infinite field k with p as its prime
ideal in k[X1,⋯,Xn]. Let P be a rational normal point on V∕k. It is proved that (1)
for a generic hyperplane Hu through P,(p,Hu) is a prime ideal and (p,Hu) is
quasi-absolutely (absolutely irreducible) if p is quasi-absolutely (absolutely
irreducible). (2) It is nol true in general that V ∩ Hu is normal at P; however,
V ∩ Hu is normal at P if the local ring of V∕k at P is also Cohen-Macaulay
(Theorem 8).