  In this paper, the dynamics of spontaneous shape fluctuations of a single,
giant quasi-spherical vesicle formed of a single lipid species is revisited
theoretically. A coherent physical theory for the dynamics is developed based
on a number of fundamental principles and considerations and a systematic
formulation of the theory is also established. From the systematic theoretical
formulation, an analytical description of the dynamics of shape fluctuations of
quasi-spherical vesicles is derived. In particular, in developing the theory we
have made a new interpretation of some of the phenomenological constants in a
canonical continuum description of fluid lipid-bilayer membranes and shown the
consequences of this new interpretation in terms of the characteristics of the
dynamics of vesicle shape fluctuations. Moreover, we have used the systematic
formulation of our theory as a framework against which we have discussed the
previously existing theories and their discrepancies. Finally, we have made a
systematic prediction about the system-dependent characteristics of the
relaxation dynamics of shape fluctuations of quasi-spherical vesicles with a
view of experimental studies of the phenomenon and also discussed, based on our
theory, a recently published experimental work on the topic.
