REFERENCES 159 



3. Compare a piece of meat with a tip of a growing plant. In 

 what ways do they differ? 



SUGGESTIONS 



1. Make a list of some of the characteristics of a tree and another 

 list of those of the horse, and underscore those that are common to 

 both. 



2. Procure an egg and open it in a small dish. Note the absence 

 of grit when a bit of the albumen is rubbed between the fingers. 

 Place a small quantity of the albumen in water to see if it sinks. 

 Then boil the water and note the effect. Vinegar or alcohol poured 

 on some of the albumen will produce the same effect. Try it. 



3. Take a bit of moist clay the size of a walnut. Into the soft 

 mass press a pebble the size of a pea. Procure a small box just large 

 enough to hold the mass. Mold the mass to the form of the box 

 and place it inside. The box represents the cell wall; the clay repre- 

 sents the protoplasm ; and the pebble, the nucleus of a cell. Old cells 

 may lack the nucleus and protoplasm, and an empty box of any form 

 would therefore represent them, except that usually the sides of a 

 " dead " cell are packed closely together. 



4. Coat a small plant with a thin smear of vaseline, and note the 

 effect. The vaseline prevents the loss of water, and the entrance and 

 exit of gases. 



5. Burn a match. What remains is mineral matter. 



REFERENCES 



Some good textbook in Botany. 



Hand Book of Nature Study. Comstock. 



Plant Culture. Goff. 



Study of Corn. Shoesmith. 



Farmers' Bulletins. Washington, D. C. 



195. Simple Exercises Illustrating Some Applications of Chem- 

 istry to Agriculture. 



218. The School Garden. 



408. School Exercises in Plant Production. 



