44 Lessons in Nature Study. 



time. They have to do this in order to grow. 13. Note 

 how it acts when teased. At first it attempts to escape, 

 then it defends itself with its claws. 



Read to the children about the crayfish ; how it burrows 

 in the earth in summer, bringing much dirt to the surface, 

 and digging wells to find water in dry seasons. Tell that in 

 this manner they are a great benefit to plants, but that they 

 often do much damage by making holes in levees along the 

 Southern rivers. 



Older pupils may dissect crayfishes when dead and mount 

 the parts upon card for more special study. If they desire 

 to prepare some crayfishes for permanent collection, first 

 soak them in a solution of glycerine, alcohol, and arsenic 

 for several days ; then remove, rinse, and dry before 

 mounting. The same solution is good for preparing worms, 

 caterpillars, etc. 



The Turtle. 



Some common kind of turtle is most desirable. If pos- 

 sible, the turtle should be brought into school and kept 

 there several days before the lesson is given. In addition 

 to a living turtle it is well to have one or more preserved 

 turtles, turtle eggs, skulls, etc., and some ornaments made 

 of tortoise-shell. 



Where does the turtle live ? Do all turtles live in water ? 

 Do they always live in water ? What do we call creatures 

 which live partly on land and partly in the water ? Am- 

 phibians. Does a turtle breathe by lungs or gills ? Give 

 reason for your opinion. Can you find its nostrils ? Exam- 

 ine its beak. Has it any teeth ? Why not ? Is its blood 

 warm or cold? Examine the shell Of how many scales 

 is it composed ? Observe the breast-bone. See what bright 

 eyes he has. Why does he not run away when teased ? 

 What does he do ? Some turtles have a soft shell like 

 leather ; others can shut up their shells like a box. Tor- 

 toise-shell is very valuable for ornaments. Eggs and flesh 

 of turtles are very good for food. 



