7 o THE BOOK OF NATURE STUDY 



character of the food stored up varies with the plant. Perhaps 

 the food most commonly found is starch, which is present in the 

 underground stem of bracken, the tuber of potatoes, and the corm 

 of the Crocus ; the leaves of bulbs often contain sugar. Arti- 

 choke tubers contain another carbonaceous substance, called 

 inulin, so too do those of the perennial sunflower. 



SUGGESTIONS FOR PRACTICAL WORK. i. Plant bulbs of Onion, 

 or some other plant, in damp sawdust, noting the position of the 

 roots, of the buds, and of the new bulbs. Onion is mentioned as 

 the cheapest bulb procurable. 



2. Grow tubers of potatoes in damp soil, some in light and some 

 in darkness. Compare the growth of the two, and make drawings 

 at regular intervals. 



3. Plant corms of crocus in sawdust, and make observations at 

 intervals of two or three months. To do this, draw the external 

 appearance of the corm and then cut a median vertical section 

 of it. 



4. Look for contractile roots of crocus in March or April, and 

 for droppers in tulips. 



5. Compare the underground structures of the Lesser Celandine, 

 the Parsnip, the Pignut, and the Gladiolus. Decide whether they 

 are roots or underground stems. The important fact to bear 

 in mind here is, that stems bear leaves and roots do not. 



6. Examine the scales of the Snowdrop, Onion, Tulip, and 

 Hyacinth. See which are entire scale leaves, and which are 

 parts of foliage-leaves, the blades of which have withered. 



7. Determine the nature of the food stored up, whether starch 

 or sugar. The former can be tested with iodine, the latter by 

 tasting. 



8. Compare the bulb of a Lily with that of a hyacinth, noting 

 the difference in the arrangement of the scales. In the former, 

 the scales simply overlap at their margin, and the bulb is said 

 to be scaly ; in the latter the outer leaves completely ensheathe 

 the inner portions of the bulb, which is then described as 

 tunicated. 



9. Count the number of plants produced by a single Strawberry 

 plant. 



