CHAPTERS ON EVOLUTION. 



Hence arises the technical name of Gymnosperms (" naked-seeded ") r 

 applied to the pines, firs, and their allies. 



The foregoing types constitute collectively the "Flowering" 

 plants of the botanist. Ranking below these plants, however, is a 

 number of types containing plant- organ isms of highly characteristic 

 nature. Thus the Ferns, Horsetails (Equiseta), and Club- 

 mosses or Lycopods, form one section of the " Flowerless " 

 plants. In these forms the true plant arises not directly 

 from a seed, as in the higher orders of plant-life, but from 

 a curious leaf-like structure called a prothallus, which in 

 its turn arises from the spore or germ of the parent plant. 

 Thus from the spore of a fern, falling from the back of its 

 frond, springs the leaf-like " prothallus." On the under 

 surface of this body are developed organs giving 

 rise in turn to the young fern, which is thus developed 

 intermediately and indirectly from its parent. This 

 character, united with others, which need not be specified 

 here, serves to render the fern type clear and indivi- 

 dualised. It may be added, however, that the stem in 

 such plants grows chiefly at its summit, and that its 

 leaves or " fronds," which bear the reproductive organs,, 

 exhibit a forked arrangement of their veins. 



Equally " flowerless " with the ferns and their neigh- 

 bours are plants which, however, rank below these well- 

 known forms in the botanical scale. Thus the Muscinea, 

 or Mosses and Liverworts, appear as a distinct type of 

 lower plants which are composed solely of ." cells," and 

 which do not possess true " roots " comparable with 

 those of higher plants. And in the lowest of the plant 

 world we meet with the Seaweeds, Fungi, and a host of 

 LEAF'OF TULIP, microscopic plants, equally "flowerless," equally cellular 

 in composition, and which, moreover, do not develop the 

 stem and leaves of the mosses. Many of these lower plants are 

 represented by single " cells ; " the well-known Diatoms, the Yeast 

 Plant (Fig. 19), and many others illustrating 

 such a constitution; whilst a mushroom or 

 other fungus is simply a mass of cells, and 

 nothing more. 



These details prove that the plant world 

 exhibits a constitution in which "types" ap- 

 pear as prominently as in the animal kingdom. 



FIG. IQ. YBAST PLANTS. T-. .1 -^ j-i i_ i_ ^i. . *.\. 



Furthermore, it can readily be shown that the 

 plant types are not more distinctly separated from one another than 

 are those of the animal world. It is demonstrable, for instance, that 

 the Alga or Seaweeds are connected by intermediate forms with the 



FIG. 18. 



