with an exponent $x=1.35\div2.0$, with a lower limit of the mass function in the range $\simeq0.1\div0.3\Msun$ ( a total absence of low mass stars): a conclusion opposite to that found recently by [@Mand96].

\[M55tot\]

An original work on M55 is in [@Irwin84]. They studied the radial star count density profile using photographic material digitalized with the *Automatic Plate Measuring System* (APM) of the Cambridge University. [@Irwin84] used a single photometric band, which did not allow them to lower the contribution of the field stars in the construction of the radial star counts. Nevertheless in this work (never repeated in other clusters), the authors reach some interesting conclusions: they claim one of the first evidences of mass segregation (even if they cannot quantify it); the central stellar luminosity function seems to be flat (with a corresponding mass function having a slope of $x\simeq0.0$) with a partial deviation from the King models. Moreover, they claim the presence of 8 short period variables, at the limit of their photometry, compatible with contact binaries of W UMa type. This last point is interesting for the presence of a large population of Blue Straggler (BS) stars in M55 to which the variables of [@Irwin84] could 