Page 26 Advertisements Column 5

Otago Witness, Issue 3555, 2 May 1922, Page 26

Measurements with newly-designed instruments have shown that tree trunks may not enlarge for many days, or even weeks, after leaves, flowers, and branches have begun to grow. In the curious daily variation. the trunk may be actually smaller in mid-afternoon than at sunrise. The sap is assumed to ascend in a kind of expanding and contracting hose of wood-cells, and, like a hose feeding an engine, this shrinks when the tree tends to draw up sap faster than formed, and swells when the demand slackens.