  The use of a non-Riemannian measure of integration in the action of strings
and branes allows the possibility of dynamical tension. In particular, lower
dimensional objects living in the string/brane can induce discontinuities in
the tension: the effect of pair creation on the string tension is studied. We
investigate then the role that these new features can play in string and brane
creation and growth. A mechanism is studied by means of which a scalar field
can transfer its energy to the tension of strings and branes. An infinite
dimensional symmetry group of this theory is discussed. Creation and growth of
bubbles in a formulation that requires mass generation for the bulk gauge
fields coupled to the branes is also discussed.
