no A FIELD GUIDE IN NATURE-STUDY 



The young plants. The problems of the young plants are (i) if the 

 seed is on the surface to get into the ground; (2) if the seed is underground 

 to get its stem and leaves out to the air; (3) to break out of its seed coats 

 and get rid of them. 



Getting out of the ground. Review your sketches above and answer 

 the following: Which of these little plants have the same method of getting 

 out of the 'soil ? What mechanical device does the corn use in getting out ? 

 Why does not the bean come up in the same way ? Can you see any prob- 

 able reason for the fact that the bean brings up its cotyledons while the 

 pea does not ? 



1. Stick a long, sharp straw vertically into the top of the part of the 

 bean plant that first appears. Fasten a piece of glass immediately over 

 the upper end of the straw. With a dot of ink mark on the glass the posi- 

 tion of this end. Do this every hour or two for a whole day. How is this 

 part of the plant moving ? 



2. Plant about twenty-five beans in a space 4 by 8 inches and lay a 

 brick over them. Can they lift the brick as they germinate ? Devise or 

 find an experiment (describe it here and record the results) to show the 

 upthrust of the growing tip of the corn plant that first appears, expressed 

 in grams or ounces. 



3. Measure the volume of five dry lima beans. Soak them overnight 

 and again measure their volume. Find the volume of the water they have 

 absorbed. How much have they increased in volume ? 



4. Fill a narrow-mouthed bottle with dry peas and pour in water to 

 fill it completely. Put in a cork and fasten it with wire or strong string. 

 Let it stand for a day or two. What happens and why ? 



5. Might such expansive power be of service to the plant in break- 

 ing out of the soil? Devise or look up an experiment to measure this 

 expansive force of a seed in grams or ounces. Try it. Describe the 

 apparatus and results. Is its force great enough to be of any real 

 use? 



6. Penetration of roots. Scatter some radish and sunflower seeds on the 

 surface of the moist earth in a flowerpot. Cover with a piece of glass and 

 watch as they germinate. Draw a radish seedling to show the root hairs. 

 Draw the sunflower to show the position assumed in trying to get the root 

 tip into the soil. Pick up a radish seedling the root of which is well covered 

 with root hairs. What comes with it? Can you see how this helps the 

 plant to get into the soil ? Did you find root hairs on root tips of radish 

 plants growing in the soil? Read up the function of the root hairs and 

 record it here. Why must one be careful to take up considerable soil when 

 transplanting ? 



