16 SOUTH AFRICAN BOTANY 
could get no more. Hence this shows that oxygen is one of 
the conditions necessary for germination. 
QUESTIONS ON CHAPTER I. 
1. Give an account of the uses and the behaviour during 
germination of the cotyledons in the various seeds whose 
germination you have watched. 
2. What are the food substances commonly stored up in 
seeds? In what form do they occur, and by what tests would 
you recognize them? How do they become available to the 
young plant at the time of germination ? 
3. What conditions are necessary to ensure germination ? 
Describe any experiments you have performed illustrating your 
statements. 
4. Explain the terms: micropyle, testa, endospermous, 
plumule, hypocotyl, germination, and embryo, 
5, Describe the structure of a broad-bean seed, and contrast 
it with that of a maize seed. 
6. Compare the germination of a sunflower seed with that 
of the onion seed. 
7. What do you understand by the embryo of a seed ? 
Select any three of the following seeds :— 
Mealie, Castor oil, Mustard, Pine, 
and (a) describe the embryo and its parts, and sketch it; (b) 
state what happens to the different parts of the embryo on 
germination and mention their functions. 
8. Show by means of drawings, with short explanatory notes, 
how the cotyledons of the pumpkin or the water-melon become 
freed from the seed-coat. 
9. Describe the structure and germination of a pine seed. 
Compare its germination with that of any monocotyledonous 
seed you have studied, pointing out how the cotyledons differ 
in function and behaviour in the two seeds, and sketching 
stages in their germination. 
10. Make sketches to show the structure of the seed of the 
broad bean, and write a brief description of the seed, 
11. What is the difference between an albuminous and an 
exalbuminous seed? Give examples of each kind. State what 
