in Fig. 4 and a correction for this would then move the galaxy towards the T-F mean line.

A second mechanism to leave the outliers in the position where they are in the T-F relation would be by mass loss, within R$_{25}$. This could be caused, for example by disruption or ablation of a part of the dark halo due to strong interactions in the group. If the galaxy loses mass, in first approximation it would move to the left of the diagram. We then calculated how much mass the outliers had to lose in order to move from the position they should have (to lie on the T-F relation) to their actual position in the diagram, if mass-loss alone were acting. The answer is an impossible number – 300-500% of the total mass – making this mechanism very unlikely. We then conclude that the reason why the low-mass galaxies are off the T-F relation is most probably due to enhanced star formation and not mass loss but could be a combination of both. Two galaxies which may have suffered truncation are HCG 89d and HCG 96d, the most deviant galaxies from the T-F relation, which have morphological types Sm 