Metaphyta Pteris. 1 1 3 



CHAPTER VIII. 



METAPHYTA VASCULAR I A. 



SECTION I. FILICES PTERIS, 



IN discussing the morphology and life-history of the fern 

 we are upon more familiar ground ; the various parts of the 

 adult plant, and its habit of producing much simpler inter- 

 mediate plants capable again of giving rise to the plant 

 from which it was itself developed, are all matters of common 

 knowledge. It may be well, however, to summarise that 

 knowledge in technical terminology. 



Starting from the fern, commonly so called, we are able 

 to distinguish an underground stem or rhizome from which 

 roots are given off. We can, moreover, differentiate shoots 

 springing from this rhizome and fronds or leaves, usually 

 of large size, which appear above ground, and constitute the 

 visible part of the plant. On the under surface of these 

 fronds at certain seasons, and covered over and protected 

 by an inturning of the leaf, or a scale-like projection of it, 

 are to be found collections of brown granular-like bodies, 

 known as sporangia, from which can be shaken a fine dust, 

 composed of what are popularly and scientifically known as 

 spores. These spores, if sown in a suitable soil, germinate 

 and form small flattened green plants, anchored to the ground 

 by minute rootlets, and not exhibiting any differentiation 

 into the stem, root, leaves, &c. which characterised the true 

 fern. To this organism the term ' prothallus ' has been 

 applied. It will be known throughout this chapter as the 

 tnallus. Upon this thallus male and female reproductive 



