It thus seems reasonable to explain the shear modulus on the basis of the bending energy of the system. However, some results render such a model unlikely. We have noticed that with increasing charge density the shear modulus shows saturation when less than 10% of the surfactant molecules are charged. Furthermore, the modulus increases strongly with increasing surfactant concentration. Both effects would be difficult to understand on the basis of the bending energy. It is mainly for these reasons that we would like to rule out this model at present even though it looks very appealing.