Fig. 61.—A, B, young; C, nearly ripe archegonium of Funaria, optical section, × 150. D, upper part of the neck of C, seen from without, showing how it is twisted. E, base of a ripe archegonium. F, open apex of the same, × 150. o, egg cell. b, ventral canal cell.
Owing to their small size the spermatozoids are difficult to see satisfactorily and other mosses (e.g. peat mosses, [Figure 64], the hairy cap moss, [Figure 65], I), are preferable where obtainable. The spermatozoids of a peat moss are shown in [Figure 60], D. Like all of the bryophytes they have but two cilia.
The archegonia ([Fig. 61]) should be looked for in the younger plants in the neighborhood of those that bear capsules. Like the antheridia they occur in groups. They closely resemble those of the liverworts, but the neck is longer and twisted and the base more massive. Usually but a single one of the group is fertilized.
Fig. 62.—A, young embryo of Funaria, still enclosed within the base of the archegonium, × 300. B, an older embryo freed from the archegonium, × 150. a, the apical cell.
To study the first division of the embryo, it is usually necessary to render the archegonium transparent, which may be done by using a little caustic potash; or letting it lie for a few hours in dilute glycerine will sometimes suffice. If potash is used it must be thoroughly washed away, by drawing pure water under the cover glass with a bit of blotting paper, until every trace of the potash is removed. The first wall in the embryo is nearly at right angles to the axis of the archegonium and divides the egg cell into nearly equal parts. This is followed by nearly vertical walls in each cell ([Fig. 62], A). Very soon a two-sided apical cell ([Fig. 62], B, a) is formed in the upper half of the embryo, which persists until the embryo has reached a considerable size. As in the liverworts the young embryo is completely covered by the growing archegonium wall.
The embryo may be readily removed from the archegonium by adding a little potash to the water in which it is lying, allowing it to remain for a few moments and pressing gently upon the cover glass with a needle. In this way it can be easily forced out of the archegonium, and then by thoroughly washing away the potash, neutralizing if necessary with a little acetic acid, very beautiful preparations may be made. If desired, these may be mounted permanently in glycerine which, however, must be added very gradually to avoid shrinking the cells.
Fig. 63.—A, protonema of Funaria, with a bud (k), × 50. B, outline of a leaf, showing also the thickened midrib, × 12. C, cells of the leaf, × 300. n, nucleus. D, chlorophyll granules undergoing division, × 300. E, cross-section of the stem, × 50.