These _cryptogams_ or flowerless plants occur in far greater numbers in the world than flowering plants, but their size in most cases is very much less. Many individuals are so small, as in the case of bacteria, that a single one can only be seen after it has been magnified many hundreds of times by the microscope. Of the cryptogams some of the largest, certainly the most beautiful, and probably the best known are THE FERNS In nearly all woods one may find delicate feathery plants with graceful, usually much divided leaves that nearly always start up from the ground like a slowly opening, but somewhat fuzzy coil. (Figure 62.) Ferns, at least most of those that grow in America, uncoil their leaves in this way, almost without exception. The accompanying figure shows the procedure, and in addition to this character one may hunt in vain for flowers. While they bear no flowers we already know that nature could not leave them with no means of reproduction without abandoning them to a childless old age and the consequent extinction of the race of ferns. So far from the truth is this that ferns make up a goodly proportion of the world’s vegetation, and there are many hundreds of different kinds known. The lack of flowers, of course, explains why ferns do not bear seeds which are matured in a fruit or ripened ovary. On the back of the leaves of most ferns, along or near the edges of the finer subdivisions, one may [Illustration: FIGS. 61-63.--COMMON WOODLAND FERN Fig. 61. A general view. Fig. 62. Its uncoiling spring condition. Fig. 63. The back of one of the smaller divisions of the leaf showing the collection of spore cases (sori). These are sometimes borne on special leaves, but in most of our American kinds on the backs of ordinary foliage leaves.] find, at the proper season, collections or rows of tiny, usually brownish dots. These contain often thousands of microscopic objects known generally as _spores_, and from this fact the dots are called spore-cases, or more technically _sori_. (Figure 63.) The process by which new plants are formed is a [Illustration: AERIAL ROOTS OF FIG TREES HANGING OVER THE EDGE OF A CAVE IN THE RAIN FOREST, SAN LORENZO, SANTO DOMINGO. (_Photo by the author. Courtesy of Brooklyn Botanic Garden._)] [Illustration: VENUS’S FLYTRAP, AN INSECTIVOROUS PLANT OF THE SOUTHEASTERN UNITED STATES. The fringed valves of its leaves close together when an insect alights between them. (_Courtesy of Brooklyn Botanic Garden._)] somewhat complicated one, but the spores in these brown dots are the agency which makes reproduction possible, and the actual mechanism of it, one of the most interesting achievements in plant life, will be described in the chapter on “How Plants Produce Their Young.” Sometimes the spores are not borne on the backs of ordinary foliage leaves but on special leaves that bear, very often, nothing else.