ioo BOTANY 



elaborate, and instead of originating nothing beyond 

 the. spores and certain outgrowths to protect them, it 

 grew to be self-supporting, by producing cells or areas 

 of cells which contained the chlorophyll. Before it 

 succeeded in making chlorophyll for itself it was com- 

 pelled to derive all its nourishment from the plant which 

 bore the ovum that gave rise to it. This ovum never 

 left the archegonium in which it arose. The sporocarp, 

 as the spore-containing structure is called, originated 

 accordingly in the cavity of the archegonium and was 

 able thus to feed on the parent plant. 



We find this stage in the evolution of the land plant 

 represented to-day by the mosses. The plants which 

 bear the ova and sperms are very small, seldom more 

 than an inch in height. They have a very slender stem, 

 bearing a number of delicate leaves, and are anchored 

 to the soil by a number of rhizoids which spring from 

 the bottom of the stem (Figs. 37, 40 B). The sperms 

 are produced in antheridia, which may be found at the 

 tops of some of the stems among the crowd of leaves 

 arising there (Fig. 38). The ova are similarly situated 

 at the tops of other stems ; each is developed singly in 

 an archegonium, a bottle-shaped body with a long neck 

 (Fig. 39). The sperm can only reach the archegonium 

 when the moss plants, which grow thickly together, are 

 wetted by rain or dew, as it must transport itself by 

 swimming. When it reaches the archegonium it makes 

 its way down the neck of the latter and fuses with the 

 ovum in the swollen basal part. The stem and leaves 

 of the moss plant are very simple in structure; the 

 former shows a protective outer layer or epidermis and 

 an interior mass of delicate thin-walled cells. In the 

 centre a strand of them is marked off from the rest by 

 their small size and in some cases by their altered cell 

 walls ; here we have the first indication of a conducting 

 system in the land plant. The leaves are flat plates of 



