Material and Equipment 291 



is convenient. A tin pail, with a cover having a hinge 

 in the middle, so that one-half the cover can be opened, 

 is also convenient. Tinsmiths make them to order at a 

 small cost. 



Instead of alcohol a 5% aqueous solution of For- 

 maldehyde (Formalin) may be used. This is very 

 much cheaper than alcohol and preserves some deli- 

 cate organisms like jellyfishes beautifully. Alcohol, 

 however, is better for general use. 



On Raising Insects for Study. The life history of 

 insects is exceedingly interesting. To actually observe 

 this life history is worth considerable trouble, even if 

 that were necessary to secure the specimen. Seeing 

 the actual transformation of an insect is a revelation 

 compared with merely reading an account of it. But 

 insects are very easily reared. The simplest and, in 

 many localities, the most convenient insect for study 

 is the "potato-bug." Its eggs are found on the under 

 side of the leaf of the potato, where they can be readily 

 watched while hatching. It requires but little atten- 

 tion to see this beetle actually lay its eggs. Dragon- 

 flies often deposit their eggs when held in the hand, 

 and moths kept in confinement lay their conspicuous 

 eggs where they can readily be seen. In the case of 

 the potato-beetle, it is an easy matter to watch the 

 gradual transformation of the egg into the larva, and 

 to observe this transforming itself into the adult beetle. 

 But their history is not so interesting as that of the 

 common fly, butterflies, and moths. 



Flies can be reared for study in the following way: 

 (i) Soak some beans for a week or two; (2) place 

 soaked decaying beans, or other decaying substance, 

 in a dish covered with a bell jar (a common saucer 

 covered with a tumbler will do for a moist chamber); 

 in warm weather flies are attracted by the odor, and if 

 carefully watched they can be seen projecting a tube 

 under the cover into the decaying substance. The 



