National Geographic : 1925 May
MARVELS OF FERN LIFE © Painting by E. J. Geske HOVW FERNS REPRODUCE A single spore-case (sporangium) of a "true fern " (Family Polypodiaceae) is shown in suc cessive stages of discharging its minute brownish spores in figures i, 2 and 3. Figures 4, 5, and 6 represent stages in the growth of the green prothallium, or sexual plant, which develops from a single spore and bears both male and female organs. A motile male element (spermatozoid) is shown in figure 7. From a single fertilized egg cell the tiny new fern plant arises, remaining attached to the prothallium (figure 8) until large enough to lead an independent existence. Figures i, 2 and 3 are enlarged 75 times ; figures 4 and 5, 150 times ; figure 6, in times ; figure 7, 450 times, and figure 8, 8 times. Ferns reproduce also without the agency of sex, by means of " bulblets " and buds which grow upon the leaves. Figure 9 shows (magnified two diameters) a bulblet of the Bladder Fern (see under Plate XVl) with young plant attached. Figure o1shows at natural size a bud of the Soft Holly-fern, developing a little plant.