SEEDS AND SEEDLINGS. 55 



Make lists of the various seeds you have examined, arrang- 

 ing them according to (1) the presence or absence of endo- 

 sperm ; (2) the number of cotyledons in the embryo ; (3) the 

 hypogeal or epigeal character of the cotyledons ; and (4) the 

 nature of the reserve food- substances. 



QUESTIONS ON CHAPTER II. 



1. How can you show that water is essential for the germination of 

 a seed ? Why is the young plant in a seed said to be "dormant " ? 



2. Give the results of experiments you have made as to the volume 

 of water which a Broad Bean seed can absorb as compared with its own 

 volume. 



3. How could you prove that a germinating seed respires (breathes), 

 just as a living animal or a human being does ? 



4. How could you prove that germination does not occur in the 

 absence of oxygen ? 



5. Why do seedlings grow badly in soil that is too liberally watered? 

 How could you measure and compare the amount of air in different 

 samples of soil ? 



6. Why should seeds not be planted very deep, nor merely laid on 

 the surface of the soil ? 



7. How could you prove that warmth is required for germination, 

 and how could you find, roughly, the best (optimum) temperature 

 for germination in the case of some particular plant ? What is meant 

 by (a) the minimum, (6) the maximum, germination- temperature of a 

 plant ? 



8. What are the effects of darkness and of light on the germination 

 of seeds ? 



9. How could you prove that a germinating seed loses in weight 

 when grown in darkness, that the loss is due largely to the oxidation 

 (or burning) of carbon, and that the cotyledons contain carbon ? 



10. Compare the food stored in a Bean seed with that supplied to 

 young birds in eggs and to young mammals in milk. 



11. What is a carbohydrate? Mention the chief carbohydrates, 

 stating how they are distinguished from each other. 



12. What is a proteid? How do proteids differ from carbo- 

 hydrates ? By what simple teats could you detect the presence of a 

 proteid ? 



13. How are oils distinguished from carbohydrates and proteids ? 



