If a plant with ripe archegonia is placed in a drop of water, with the lower surface uppermost, and at the same time male plants are put with it, and the whole covered with a cover glass, the archegonia and antheridia will open simultaneously; and, if examined with the microscope, we shall see the spermatozoids collect about the open archegonia, to which they are attracted by the substance forced out when it opens. With a little patience, one or more may be seen to enter the open neck through which it forces itself, by a slow twisting movement, down to the egg cell. In order to make the experiment successful, the plants should be allowed to become a little dry, care being taken that no water is poured over them for a day or two beforehand. The first divisions of the fertilized egg cell resemble those in the moss embryo, except that the first wall is parallel with the archegonium axis, instead of at right angles to it. Very soon, however, the embryo becomes very different, four growing points being established instead of the single one found in the moss embryo. The two growing points on the side of the embryo nearest the archegonium neck grow faster than the others, one of these outstripping the other, and soon becoming recognizable as the first leaf of the embryo (Fig. 67, _A_, _L_). The other (_r_) is peculiar, in having its growing point covered by several layers of cells, cut off from its outer face, a peculiarity which we shall find is characteristic of the roots of all the higher plants, and, indeed, this is the first root of the young fern. Of the other two growing points, the one next the leaf grows slowly, forming a blunt cone (_st._), and is the apex of the stem. The other (_f_) has no definite form, and serves merely as an organ of absorption, by means of which nourishment is supplied to the embryo from the prothallium; it is known as the foot. [Illustration: FIG. 67.--_A_, embryo of the ostrich fern just before breaking through the prothallium, × 50. _st._ apex of stem. _l_, first leaf. _r_, first root. _ar._ neck of the archegonium. _B_, young plant, still attached to the prothallium (_pr._). _C_, underground stem of the maiden-hair fern (_Adiantum_), with one young leaf, and the base of an older one, × 1. _D_, three cross-sections of a leaf stalk: i, nearest the base; iii, nearest the blade of the leaf, showing the division of the fibro-vascular bundle, × 5. _E_, part of the blade of the leaf, × ½. _F_, a single spore-bearing leaflet, showing the edge folded over to cover the sporangia, × 1. _G_, part of the fibro-vascular bundle of the leaf stalk (cross-section), × 50. _x_, woody part of the bundle. _y_, bast. _sh._ bundle sheath. _H_, a small portion of the same bundle, × 150. _I_, stony tissue from the underground stem, × 150. _J_, sieve tube from the underground stem, × 300.]