The microscopic investigation in navashin-fixed material of Beilschmiedia tawa has shown that this species is a typical example of a tree with facultatively colored heartwood. Microtechnological measurements, as for instance of the shrinkage or the sorption or other features, have been proved suitable to determine whether or not the heartwood substances, which are formed in the storage tissue, have spread out into the cell walls of the surrounding tissues. Furthermore, it can be shown from the above mentioned results that cytological and physiological studies in wood must be based on the anatomical structure but may help at the same time towards a better understanding of this structure. The investigations in Beilschmiedia tawa are only one example of the suitability of subtropical or tropical timbers for this type of investigation. It may be hoped that, thanks to a close co-operation with research stations overseas, this beginning may be continued.