GYMNOSPERMiE. 



109 



conditions. Poliar appendages were probably given off, and a sort of plantlet with 

 strictly cellular root-like and leaf-like organs would thus have come into existence, capable, 

 like the Mosses of the present day, of agamous reproduction. Such a primordial cellular 

 plant constitutes the first stage of growth, not only of Mosses and Hepaticse, but also of 

 Perns, Equisetaceae, Lycopods, and Ophioglossese. They are developed from the spore 

 and closely resemble the lower Algae in their purely cellular structure. 



Saporta and Marion also regard the relatively early or late appearance of sexual organs 

 in the life of a plant as exerting a predominant influence on its susceptibility to become 

 differentiated or modified through the force of the changing circumstances which surround 

 it. Those among the primitive terrestrial Algae in which sexuality was deferred until late 

 had a longer period of purely vegetable life ; and were thus not only more susceptible to the 

 influence of new conditions, but had a longer time in which to adapt themselves to them, 

 and so become diversified in type. Among the results of this elaboration they place the 

 existing Mosses and Hepaticae. In the Mosses the spore gives birth to a conferva-like 

 thallus, called the Protonema, a reversion in all probability to a primitive ancestral stage. 

 The growth of this elementary thallus, or purely cellular plant, is never arrested by the 

 development of sexual organs, and is thus peculiarly susceptible to differentiation ; foliar 

 buds are given off in places from its ramifications,^ the increase of cells at these points 

 assumes a regular plan, and little by little small laminae take the form of leaflets borne on 

 a stem supported by radicles. These radicles are capable of producing new plants and 

 propagate so energetically that extensive carpets of moss may be formed without the aid 

 of reproductive organs, which, indeed, are rarely present in some species. When present, 

 however, they are of great morphological importance, and are distinguished as male, or 

 " antheridia," and female, or " archegonia." The male is generally a club-shaped body, 

 attached to the stem, filled with small and crowded cells, each of which contains an anthero- 

 zoid. The female organs, when mature, are in shape of a flask with a long neck, bulging 

 from a narrow base and composed of a number of cells, of which the central, basal one is the 

 largest and develops the oospore. At maturity the antherozoids escape by the rupture of 

 the antheridium and enter the archegonium. A new plant is produced by the oospore, 

 which develops within the archegonium in which it is born and finally becomes the stalked 

 organ called capsule or fruit in the Mosses. This so-called fruit bears no resemblance 

 morphologically to the fruit of a Phanerogam, but is in reality a distinct asexual genera- 

 tion or separate plantlet, called by Sachs a " sporogonium," which gives birth to the 

 spores ; which spores, falling in damp places, give rise to a new sexual generation of 

 thallic, or moss plants. This alternate generation is unknown among Algae, and the 

 Hepaticae and Mosses therefore introduce a new point of departure, the more developed 

 and conspicuous of the two generations being very analogous to Algae, while the less con- 

 spicuous sporogone is agamous, subordinate, and incapable of disengagement from the 

 archegone in which it is formed ; yet it is fundamentally an independent plant. The 

 1 Most frequently from the root-hairs, according to Williamson. 



