deed, every biological laboratory is more or less permeated by this spirit of experimental investigation which the recent literature of biology shows may be successfully carried on even without elaborate equipment.
In keeping animals in confinement it is necessary not only to know their habitats, but also their manner of movement and whether they prefer light or darkness and living or dead food. For the investigations upon land animals carried on in the Vienna station, terraria have been constructed with especial care. The sloping bottom of the metal terrarium (Fig. 2) contains soil, with drainage for superfluous water and micro gas burners, or electric bulbs for heating. On one side of the
glazed superstructure and in the roof, ventilating screens are inserted. According to the degree of moisture needed the ground material varies from bran for meal-beetles and clothes-moths, sawdust for cockroaches, clay for bees, wasps and tiger-beetles, fine sand for leaf insects and rove-beetles and common garden soil for earthworms, glow-worms and wood-lice. Plants are used for the production of oxygen and food and with pieces of old bark and branches constitute a natural environment with its grateful shade and hiding places. To provide necessary moisture the ground is sprinkled in the early morning and during the day for the diurnal animals and in the evening for the nocturnal forms. Each day an artificial mist, or rain, is produced in the terrarium atmosphere by means of a hand atomizer or a small compression air pump.