The complete life-cycle of a liverwort thus includes two unlike generations, as that of a fern does; but it is a different generation which attains the greater development in the two cases. The ordinary fern is the spore-bearing generation; the “ordinary” liverwort is the sexual generation, and its sporing offspring is not a separate plant at all, but a mere stalked box, almost entirely dependent upon its parent. The mosses.—A moss-plant appears at first sight to be very similar in its general features to one of the higher plants; for it has a little stem, bearing flattened green leaves which build up carbonaceous food in the usual way. It has no true roots, but fine hairs penetrate the soil and do the work of roots by taking up solutions of mineral food. It is all the more remarkable, therefore, to find from its method of reproduction that the moss-plant belongs to the generation which corresponds to the prothallus stage of a fern’s life-history, and not to the leafy, sporing generation which it somewhat resembles superficially. The sexual organs of a moss are essentially of the same type as those [Pg 202] which a prothallus bears, and here also the tiny male cells gain access to the female cells by swimming through a drop of rain or dew. The result of fertilisation is an embryo which, however, grows up to form, not a plant with stem and leaves, but a stalked spore-case only. In a tuft of the moss Funaria, which is so common in all country places, several stages of development of the spore-cases may usually be seen. Fig. 156 represents a moss which is very similar to Funaria but larger. In A, the spore-case is still covered by a conical hood (c). In B, the stalk (s) has grown much longer, and the hood has dropped off. The spore-case or capsule (k) is now seen to be a pear-shaped body, closed by the lid (d). When the spores are ripe, the lid becomes detached. The mouth of the nodding capsule is still blocked, however, by a number of teeth (Fig. 156, C, p) which remain close together in damp weather. In dry weather the teeth separate, and allow the spores to fall out. When a moss spore falls in a favourable situation it germinates to form a fine, branching network of green threads, from which new moss-plants arise as buds. The obvious plant of a moss—like that of a liverwort—therefore corresponds to the prothallus generation of a fern or horsetail. Its sporing generation, corresponding to the obvious fern-plant or [Pg 203] horsetail, is a stalked spore-case, which is always more or less dependent on its parent and dies down as soon as its work of scattering the spores is accomplished. 41. THE COMMON MUSHROOM.