(c) The leaves.—Make a drawing of one of the expanded leaves. Notice that the leaf consists of a number of leaflets, and that these are again cut up into segments, or are at least deeply lobed. Notice the brown hairs clothing the leaf-stalk and the midrib. Notice the crozier-like coiling of the young fronds, and make out that when they uncoil the inside of the coil becomes the upper surface of the leaf. [Pg 184] (d) The reproductive organs.—Examine the lower surface of full-grown fronds, and notice the brown rounded patches. Dry some leaves bearing these patches and shake them over a sheet of paper. Collect the brown dust which falls from the patches; it consists of minute grains called spores. (e) The prothallus.—Sow some spores on damp soil sheltered from the direct rays of the sun. Keep the soil moist, and notice that in a few weeks the spores have grown into small, flat, green, heart-shaped plants. Each of these is called a prothallus. Pick off prothalli of different ages with a needle, float them in water, and compare the various stages of growth. In old prothalli notice a young fern plant springing up from the lower surface. Observe that as these become larger the prothalli which bear them shrivel up and die. 2. The bracken, fern.—Dig up a bracken fern, wash the earth from the roots, and compare it, point for point, with the male-fern. Notice: (a) The long cylindrical, branching, underground stem. Does it lie deeper in the ground than the stem of the male-fern? Cut the stem across and compare the section with Fig. 148, noting (i) the two concentric rings of separate vascular strands (s). (ii) The strengthening material, arranged as a brown zone (lp) just below the skin, and as an incomplete ring (ll) between the two rings of vascular strands. (iii) The softer ground-tissue (R), in which the vascular and strengthening strands are embedded. Draw the external appearance of the stem (natural size), and also the cross section (4 times natural size). (b) The roots.—Describe the roots. Do they appear to arise from any particular region of the stem? (c) The leaves.—From what part of the stem do the leaves arise? How many come up each year? What is the appearance of a young leaf before it expands? How does it differ from that of the male-fern? Draw a young leaf, and also an expanded one. Is the leaf simple or compound? Does it branch? Does the leaf of the male-fern branch? (d) The spores.—Examine the under side of the leaf, and notice the absence of the brown patches seen in the male-fern. Notice that the [Pg 185] edge of the bracken frond is folded over like a hem. Dry a frond, and then run the point of your pencil under the fold and observe the brown dust (spores) which is removed.