IN the issue of NATURE for February 2, Mr. A. Mallock requests information on styrax. I am able to supply the following information: The styrax best suited for the mounting of diatoms is obtained from the Oriental sweet gum tree (Liquid-ambar orientalis). This tree is native to the southwestern portion of Asia Minor. The balsam is a pathological secretion from the wood and inner bark. After the tree has been injured and the secretion has collected on the injured surface, the inner bark is removed and boiled in sea water—the balsam being skimmed from the surface.