  The three nucleon interaction that arises from pion and the effective scalar
and vector meson exchange components of the nucleon-nucleon interaction is
constructed and shown to be repulsive. Using several wavefunction models we
show that this interaction reduces the calculated binding energy of the
trinucleons by about 200 keV. The contributions of intermediate $N$(1440)
resonances to this three nucleon interaction and of the $D$-state component in
the trinucleon model are estimated, and shown to be small.
