252 HOPMETSTER, ON 



stem, and are remarkable for their rapid development, 

 especially in thickness, even in the early youth of the 

 plant. The fronds which follow the first frond differ 

 remarkably in form, direction, and structure. Their 

 outline is circular or reniform ; they are developed in 

 a horizontal direction, bending backwards and downwards 

 to such an extent from the point of attachment, that they 

 touch the base of the plant. Their thickness far exceeds 

 that of the upright frond ; their vascular bundles lie, not in 

 one, but in two planes parallel to the surfaces of the frond. 

 These bundles form two many-meshed nets, one close under 

 the upper side, and the other immediately above the lower 

 side of the frond ; the two net-works are united in many 

 places by frequent ramifications which pass through the 

 mass of the frond in a transverse direction. 



When the plant has attained a certain amount of vigour, 

 erect fronds are again formed, which hang over gracefully, 

 and exhibit slightly spreading forks upon which spo- 

 rangia sometimes appear. After six or eight such erect 

 fronds have been produced, a pair of simple fronds is de- 

 veloped, one on the right and the other on the left of the 

 stem. These latter fronds curve downwards. All the 

 fronds, as well the thick flat recurved ones as also those 

 which are slender and erect, are arranged accurately in two 

 lines ; this is seen clearly by cutting through the fronds as 

 far back as the primary place of attachment. The direction 

 of the frond-arrangement, judged by reference to the mode 

 of succession of two neighbouring flat fronds, is sometimes 

 to the right and sometimes to the left. A bud is usually 

 formed deep down on the hinder side of the stipes of each 

 of the erect fronds. This bud, when laid bare by the re- 

 moval of the flat frond which forms a thick covering over 

 it, becomes developed into an independent plant. 



It is not difficult to conjecture the part which the thick 

 recurved fronds play in the economy of the plant. They 

 prevent the drying up of the place of growth. The thick 

 covering which they form causes that portion of the bark 

 of the trunk of the tree upon which the fern grows, to be 

 retentive of moisture. Those species of the same genus 

 whose fronds spread over the surface of the ground, thus 



