SEED GERMINATION 73 



Conclusion. — Explain briefly why one thermometer 

 should have shown a higher temperature than the other. 

 If more than one kind of seed is used, tell why large seeds, 

 such as peas or beans, should develop higher temperatures 

 than smaller seeds, such as oats or barley. Why is it that 

 if grain becomes wet in the bin while the weather is warm, 

 it will heat? Name, now, two things which a seed takes 

 in and two which it gives off during germination. 



61. How Size of Seed affects Growth of Young Plant. 



— Now that we have found that germinating seeds give 

 off heat, let us take up the question of how the amount 

 of food stored in the seed affects the amount of heat or 

 energy generated. In other words, since the reserve food 

 in the seed is to feed the embryo, how does the amount 

 stored there influence the strength and vigor of the young 

 plant? 



EXERCISE 24 



Object. — To show the use of the reserve food, and 

 how the amount present influences the growth of the 

 young plant. 



Procedure. — Carefully cut away the endosperm from 

 four grains of com, taking care not to injure the embryo.' 

 The cutting is more easily done when the grains have been 

 soaked in water for a couple of hours. Plant these in a 

 row in a cigar box of sand; and in another row, plant 

 four whole grains of com. 



Plant two rows of beans without injuring the seeds in 

 any way. When they have pushed their seed leaves, or 



' It is a sing^ar fact that mutilation of a seed hastens ger- 

 mination. Even if the embryo is not injured in any way, this 

 operation causes it to germinate quickly and grow rapidly. 

 The effect of the loss of the endosperm is seen later as it weakens 

 from lack of food. 



