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THE POPULAR SCIENCE MONTHLY 



deed, every biological laboratory is more or less permeated by tbis 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 

 terrariura (Fig. 2) contains soil, with drainage for superfluous water 

 and micro gas burners, or electric bulbs for Jieating. On one side of the 



FiQ. 5. View of thb Glass House fob Low Tempebatures. 



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 mois- 

 ture 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 atmos- 

 phere by means of a hand atomizer or a small compression air pump. 



