  The amount of mass contained in low-mass objects is investigated anew.
Instead of using a mass-luminosity relation to convert a luminosity function to
a mass function, I predict the mass-luminosity relation from assumed mass
functions and the luminosity functions of Jahreiss & Wielen (1997) and Gould et
al (1997). Comparison of the resulting mass-luminosity relations with data from
binary stars constrains the permissible mass functions. If the mass function is
assumed to be a power law, the best fitting slope lies either side of the
critical slope, -2, below which the mass in low-mass objects is divergent,
depending on the luminosity function adopted. If these power-law mass functions
are truncated at 0.001Msun, the contribution to the local density of stars lies
between 0.016 and 0.039 Msun pc^-3, in conformity with the density measured
dynamically from Hipparcos stars. If the mass function is generalized from a
power law to a low-order polynomial in log(M), the mass in stars with M<0.1Msun
is either negligible or strongly divergent, depending on the order of the
polynomial adopted.
