5. Bulbs.—Cut an onion or snowdrop bulb down the middle, and draw what you see, marking on your drawing the outer scale leaves, the swollen bases of last year’s leaves, the young leaves in the middle, the short, thickened stem, and the roots. Also cut other bulbs across and again draw. What is the similarity and what is the difference between these bulbs and such a bud as a cabbage? Also examine hyacinth, tulip and daffodil bulbs. Put them in glasses with water touching their bases, and watch them grow. What do they live upon? 6. A crocus corm.—Obtain a few crocus “bulbs” in the early winter. Observe the tough outer tunic springing round the edge of a circular scar on the base. If there are any roots they come off from the scar. Take off the tunics from one “bulb” and observe the bud or buds at the top of the white mass inside. Other tunics cover the buds. Cut lengthwise through the mass of the “bulb” so as to bisect the largest bud. Separate the parts of the bud with a needle and notice (a) the thin outer leaves, (b) the young foliage leaves, (c) the flower-sheath and flower. Pour a drop of iodine solution on the cut white mass (the stem) below the bud. It turns blue. Why? [Pg 82] What is the principal difference between a crocus “bulb” and the bulb of an onion, hyacinth, or tulip? A true bulb is mainly composed of swollen leaves or leaf bases; in the crocus the thick, rounded stem makes up most of the bulk. It is better, therefore, to speak of a crocus corm, to indicate the difference. Plant the remaining corms and examine them at intervals for a year. Notice the formation of the roots, the lengthening of the buds, the formation of the flowers, the activity of the foliage leaves after flowering (why?), the withering of the roots and leaves in summer, and the growth of the enlarged base of the branch into next year’s corm. Creeping stems.—Instead of climbing, many stems find that the best method of spreading out their leaves is to creep along or under the ground, and give off leaves and roots at intervals. Not only does this device prevent the leaves of one node from interfering with the light and air supply of those of the next, but the plant is continually coming in contact with a fresh lot of soil. The ground ivy is an instructive example of this method of growth. The stem creeps along the ground, and at every node it gives off a pair of leaves which grow upwards, and a tuft of roots which grow down into the ground. Fig. 50.—Runner of Strawberry. (× ⅓.) The runner of the strawberry (Fig. 50) appears at the first glance to grow in a similar manner. As a matter of fact, however, the [Pg 83] apparent stem is a branch arising in the axil of one of the leaves of the last node. The branch runs along the ground and gives rise to a new shoot, and from this another branch, springing from the axil of a leaf, forms another runner. The same branch does not run on from shoot to shoot.