The construction of a small, inexpensive, water-tight maze with uniform channels has offered a problem to investigators of the behavior of the protozoans and other small aquatic animals. Mazes etched in glass have gross irregularities in the channels that are detrimental especially for unicellular animals. Small mazes without these irregularities can, however easily be constructed of lucite plastic with only a coping saw, small files, and sandpaper.' The maze-pattern should be cut through a piece of lucite with a width equal to that required for the depth of the maze. This piece is then cemented with plastic