Confining our attention to dicotyledons, we are impressed by the great variation in size of the cotyledons. Those of the bean and pea are swollen with food material and form a large proportion of the bulk of the seed. As a consequence, the seedling has enough food to enable it to grow into quite a sturdy little plant before it needs any foliage leaves. The cotyledons of the mustard and sycamore, however, are thin, and they unfold almost immediately into green leaves, and set to work to help to maintain the plant until the first foliage leaves can be formed. The cotyledons of the lupine (Fig. 9) and vegetable marrow (Fig. 10) serve a double purpose. They not only contain a store of food ready to hand, but they also set to work early to make new food, until the new leaves are sufficiently advanced to take up their duties. It should be remembered that cotyledons are makeshift leaves. EXERCISES ON CHAPTER I. 1. Make a collection of the seeds of various trees; try to find, in each seed, the cotyledons, radicle, and plumule. Which of the seeds contain stored starch? [Pg 25] 2. Soak pine and larch seeds in water for several days and then sow them, with a covering of half an inch of soil. Make notes of the number, shape, size, and behaviour of the cotyledons. How large are the seedlings at the end of the first season? 3. Make similar observations on the growth of sycamore, ash, and beech. Cover the seeds with an inch of soil. 4. Plant seeds of oak and chestnut two inches deep, and make drawings and notes of the stages of growth. 5. Investigate the structure and method of germination of a barley seed, and find out whether barley is a dicotyledon or a monocotyledon. 6. Make experiments to discover the effects, upon the germination of various seeds, of differences of temperature, moisture, and light, and write full accounts of the results obtained. 7. Draw from memory a young seedling of maize, and notice its chief peculiarities. (1898) 8. Draw the seedling of the sycamore in two or more stages, and add short notes. (1898) 9. Draw the root of any seedling that you have studied, giving its name. Mark the exact position of the root-hairs. (1898) 10. Open the nut provided. Draw what is to be found in it in one or two positions. Name the parts and give short explanations. (1901) 11. Explain, with drawings, how certain seedlings withdraw their seed-leaves from the seed-coat. (1901) 12. Describe and explain as far as you can the principal changes to be observed during the germination of a bean or pea. (1901) 13. Describe the germination of a bean, and compare it with that of a grain of wheat. (1898) 14. Describe the structure of a grain of wheat, and contrast it with that of an acorn. (1896) 15. Plant seeds in wet, sticky soil (so that the air cannot easily get to them), and compare their growth with that of similar seeds in a light, open soil.