GERMINATION 123 



budlike plumule grows upward, forming the first true leaves and 

 all of the stem above the cotyledons. As growth continues, we 

 notice that the cotyledons become smaller and smaller, until their 

 food contents are completely absorbed by the young plant. The 

 young plant now has roots and leaves and is able to care for itself 

 and may be said to have passed through the stages of germination. 



Laboratory Exercise. Examine several stages in the growth of the 

 pea or bean. Make drawings for your workbook to illustrate at least 

 three of the stages described below. 



Practical Exercise 3. Look up in seed catalogs or gardening books how 

 deep you should plant several different kinds of seeds. Is there any relation 

 between the depth of planting and the size of the seed? If so, explain this. 



Self-Testing Exercise 



When a bean seed germinates, the (1) first grows (2). 



Then it develops an (3) which draws up the (4) as it 



grows upward. Later the (5) develops. During this growth the 



(6) are used up as (7) by the (8) (9) . 



PROBLEM V. WHAT MAKES A YOUNG PLANT GROW? 



Demonstration 7. To prove that growing seeds oxidize food. 



Materials. Bottle, rubber stopper, thistle tube, delivery tube, soaked 

 peas, blotting paper, and limewater. 



Method. Put some soaked peas in the bottom of a bottle containing 

 some soaked blotting paper. Fit the bottle with a rubber stopper con- 

 taining a thistle tube and a delivery tube. 



_ Watch for evidences of growth in the bottle. At the end of forty- 

 eight hours, insert the delivery tube in a tube of limewater. Pour 

 water through the thistle tube into the bottle. What happens to the 

 limewater ? Why was water poured through the thistle tube ? 



Conclusions. Remembering what you have learned in your previous 

 experiments, account for what happened. Why did the seeds start 

 to grow? From what source did the seeds get their energy to grow? 



Write a brief statement, using proof to show that energy is stored 

 in food and that it can be released and used only by oxidation. 



What makes an engine go. If we examine the sawdust or soil 

 in which the seeds are growing, we find it forced up by the growing 

 seeds. Evidently work was done; in other words, energy was 



