Corrections

May 1982, page 28—center column, three lines above “Smectic phases”: “thin films” should be “defects.”

page 28—third column, lines following equation 2 should read: “where the nematic free energy density$φN$ is given by $φN = 1/2[K1(∇⋅n̂)2+K2(n̂⋅∇)2+K3(n̂×∇×n̂)2]$

page 29—center column, 23 lines up from bottom, should read: “r_∥^−η”

page 31—left column, last paragraph should read “.…vivid examples in three dimensions of ideas that arose in lower dimensions; one of the most exciting advances…”