RESUMO
The aim of the present study is to emphasize the applicability and versatility of the allometric equation in the biological sciences. This equation (Y = a x Mb) was introduced by Huxley (1932) for intra- and interspecific comparisons of morphological, physiological and ecological variables (Y), when they are expressed as functions of body mass (M). The regression analysis of the experimental data, plotted in a double logarithmic scale, yields a straight line, which is equivalent to the logarithmic form of the above mentioned allometric equation [log Y = log(a) + (b) x log(M)]. Only the exponent (b) can be calculated a priori for a given function, based firstly on the corresponding dimensional analysis in accordance with the MLT-system of physics, and secondly on one of the theories of biological similarity, while parameter (a) is of empirical nature. A relevant feature of the allometric equations is that they can be treated algebraically to obtain allometric ratios, mass independent numbers (MIN), and even dimensionless numbers (M0L0T0), which are valid for all organisms pertaining to the same taxonomic classification