Abstract
Methods are described which eliminate born contamination in the culture medium. Excised flax roots, grown in sterile sulture, are shown to have a boron requirement which is satisfied by 0.05 p.p.m. boron. Root growth stopped after 48 hours in media lacking boron. The boron requirement of excised roots is similar to that of whole flex seedlings. It is concluded that the observed restriction of root growth in media lacking boron is not connected with the movement of sugars into flax root cells.