1. A method of probabilistically classifying a sample of tissue of a mammalian anatomical structure, tissues of which may have various morphological and biochemical states and are classifiable in accordance therewith, comprising: illuminating the tissue sample with first wavelength electromagnetic radiation selected to stimulate in the tissues of the mammalian anatomical structure a fluorescence having spectral characteristics distinguishing between a first plurality of classifications therefor; acquiring first fluorescence intensity spectrum sample data for the tissue sample from the first wavelength illuminating step; obtaining a first quantity from first fluorescence intensity spectral calibration data, the first calibration data being from a first calibration set comprising tissues in each one of the first plurality of classifications of a statistically significant set of tissues of the mammalian anatomical structures illuminated with the first wavelength electromagnetic radiation, and the first quantity accounting for a significant amount of variation in the first calibration data and showing statistically significant differences between the first calibration set tissues in the first plurality of classifications; obtaining first probability distributions of the first calibration data as modified by the first quantity for each one of the first plurality of classifications; and calculating from the first probability distributions and from the first sample data as modified by the first quantity a probability that the tissue sample belongs in one of the first plurality of classifications.