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Well-marked differences, involving both the patterns of moisture movement and storage, have been found to separate the water relationships of yellow birch, Betula lutea Michx., in various stages of deterioration. The cumulative results of injection studies, root excavations, and an extended survey of the trends in moisture distribution in the species over a prolonged period, suggest that the locus of action of the disease is, in the first instance, in the roots, and that excessive rootlet mortalities in apparently healthy trees constitute the initial indication of a diseased condition in the species.

The movement of moisture in large woody stems under normal conditions of uptake is described. Consideration is also given to the aberrant patterns of staining characteristic of woody stems following partial injection of lower boles of standing trees. Staining patterns resulting from very drastic disruption of the normal channels of water conduction are discussed, and the results reviewed in the light of the mechanism of moisture movement in large woody stems.

Dendrographs attached to the lower boles of large trees of several species indicated little change in diametral fluctuation patterns following decapitation or severe mechanical interruption of conducting tissues. Treated and undisturbed stems of a particular species, investigated concurrently, manifested striking similarities in the amount, trend, and duration of diameter shrinkage. The results of these experiments, in company with others dealing with continued moisture movement in experimentally treated trees, jointly suggest that the water-conducting system of large wood stems is one of great coherency and stability.

Observations bearing on the rates of vertical travel of moisture in normal and treated trees of several species are presented. Differences in the speeds of movement deriving from a specific experimental treatment are analyzed statistically, and brief consideration given to a particular aspect of the mechanism of moisture movement in trees.