LABORATORY EXERCISES 45 



carefully and note the difference in the root system; also how the young 

 corn plant is still attached to the kernel. A few days later note 

 that the thick halves of the bean have gradually disappeared; also that 

 the corn kernel has decreased till little more than a shell is left. The 

 plant is drawing on its supply of food stored in the seed. Soon the green 

 leaves will begin to manufacture food from the air, while the roots will 

 draw on the supply in the soil. 



3. Plant beans in another box or pot. As soon as they appsar 

 above ground, cut off parts of the thick "seed leaves" with a knife, 

 being careful not to injure the young plant. Leave one or two plants 

 undisturbed. Note that the vigor of growth depends on the quantity 

 of plant food available, as indicated by the size of the portions which 

 were allowed to remain. Portions of the starchy upper part of the corn 

 kernel may be cut away before planting without injuring the germ. 

 Cut several kernels in this way and note the effect on germination and 

 growth. 



4. Cut five or six thicknesses of blotting paper the size of a large 

 plate, place in the plate and have another plate of the same size to turn 

 down over it. Make several of these small germinators and place 

 fifty grains of wheat, oats, or barley between the blotting paper in each ; 

 moisten the blotting paper in all but one and keep it moist. (Several 

 thicknesses of cloth may be used instead of the blotting paper if desired.) 

 Set one of the germinators in a cool place and another where it remains 

 at about the ordinary temperature of the room, 70 degrees. Place the 

 dry germinator alongside the moist one in the warm room. Set one 

 germinator in a warm, light place and another in a warm, dark one. 

 Do not let any of the germinators become dry except the one which 



' was started that way. In five or six days examine all of them and see 

 what has happened. Is moisture necessary for germination? Is light? 

 Is heat? 



5. Plant several beans in pots or small boxes of good soil; after the 

 plants appear set one box in a cool place, but where it will not freeze; 

 put another in a dark room or closet; place the remainder in a warm, 

 sunny window. Set one of the pots in the window and let it dry out; 

 plunge another in a pan of water to the top. Keep the others moist 

 but not wet. In a few days compare the growth which has been made. 

 Is light necessary? Is heat? Moisture? Do the roots need air? 



6. If there is sufficient time, a large number of other exercises may 

 be worked out, showing that plants need air, light, moisture, plant food, 



