EQUIPMENT 19 



cloth on which have been placed thirty or forty drops of 

 chloroform for every hundred cubic inches of space. A 

 convenient killing jar for insects is made by having a drug- 

 gist place in a wide-mouthed fruit jar five cents' worth of 

 potassium cyanide in small pieces, which must be covered 

 with a thick solution of plaster of Paris in water. In 

 order that the plaster may dry the jar should be left open 

 a day or two and then kept closed except when putting in 

 or removing animals. Potassium cyanide is a deadly 

 poison. A wide-mouthed cyanide bottle is convenient 

 for pupils to use in the field. 



Keeping Live Animals. With but slight trouble and 

 great profit many animals may be kept alive in the school 

 room or laboratory. Snakes, turtles, and lizards live com- 

 fortably in a covered box containing dry earth and a soup 

 plate with water. A turtle will eat fresh beef, but the 

 lizard and snake need a weekly meal of beetles, flies, or 

 earthworms. Tadpoles, newts, fish, water fleas, various 

 insect larvae, a few worms, hydra, and many protozoans 

 flourish in aquaria consisting of glass jars or dishes filled 

 with water and containing a few water plants. The water 

 need not be changed if the bulk of the plants is about one 

 fourth that of the animals. A few bits of fresh beef should 

 be given the vertebrates once a week. The aquarium 

 needs good light but not necessarily direct sunshine in 

 order that the plants may flourish and furnish oxygen for 

 the animals. Gallon battery jars to be had of the Whitall, 

 Tatum Co., of New York, serve excellent aquarium pur- 

 poses and cost but fifteen cents each. 



If animals which one can not secure in his own locality 

 are desired, they may be obtained of the following dealers: 



