272 LETTER XXril. 



curled up round the thecae, so as to lose entirely the 

 natural appearance, and to resemble a sort of inflo- 

 rescence. A striking instance of this is not uncommon 

 in bogs, in the form of a plant called the Osmund- 

 royal, or Flowering Fern (Osmunda regalis) ; a minute 

 species found in woods, and called Adder s Tongue 

 (Ophioglossum), because of its narrow inflorescence, 

 is another British example. 



Such is the first and highest degree in the scale of 

 organization among Flowerless plants. Possessing a 

 system of vessels, frequently attaining a considerable 

 size, having leaves intersected by veins, and having 

 their surface provided with breathing pores. Ferns 

 may be considered to differ from Flowering plants in 

 little except in the manner in which they are propa- 

 gated, and in the organs assigned them by nature for 

 that purpose. Next to them is arranged a small tribe 

 also possessing a system of vessels in the stem, and 

 breathing pores on the surface, but destitute of veins, 

 and having a remarkably different mode of repro- 

 duction ; you will find, indeed, that there is this 

 great peculiarity in Flowerless plants, independently 

 of all others, that no two tribes agree exactly in the 

 nature of their organs of propagation. While in 

 Flowering plants one tribe is distinguished from 

 another by slight variations in the form, or number, 

 or proportions of a few organs that they all possess in 

 common, you will find among Flowerless plants, on 

 the contrary, that every tribe has an independent and 

 peculiar provision of its own for the perpetuation of 

 the species. 



