312 The Fern Tribe. 



remark a number of narrow pale bands appearing at pretty 

 equal intervals upon some of the veins, and following their di- 

 rection. Presently afterwards the whole of the skin of the 

 leaf, where these bands are, separates from the green part he- 

 low it : in course of time, something swells and raises up th e 

 skin, till at last it bursts through it, separating the skin into 

 two equal parts, one edge of which remains adhering to the leaf. 

 At this period the cause of this swelling is discovered ; it con- 

 gists in a multitude of brown seed-like grains that are crowded 

 together very closely, and form a brown ridge. Botanists call 

 the skin which separates from the leaf, the Indusium, the ridge 

 Sorus, and the seed-like grains Thecce. In order to gain a dis- 

 tinct view of all these parts, you should cut through the leaf 

 across the sorus, just after the indusium has burst; and the 

 edges of the indusium will be distinctly visible, with the ridge- 

 like receptacle of the thecae rising up between them. 



The only means of propagating itself which the Heart's- 

 tongue possesses, resides in the thecae. It has no calyx, corolla 

 stamens, or pistil, and consequently neither fruit nor seed* 

 nevertheless it can perpetuate its kind with the same certainty 

 as the most perfect plant. The theca is not a seed, nor is it a 

 body whose functions are of a nature similar to those of a seed. 

 You require a pretty good microscope to examine it correctly ; 

 but with such an instrument you will make it out to be a round- 

 ish compressed body, seated on a jointed stalk, which runs up 

 one side of the theca. Upon examining a good many of the 

 thecae, you will no doubt remark some of them burst open; 

 and then you will find that they are hollow bodies, containing 

 a quantity of extremely minute oval grains, called Spores by 

 botanists. It is in the spores that the power of increase re- 

 sides ; every one of them will form a new plant, and conse- 

 quently they are analogous to seeds ; but as they do not result 

 from the action of pollen upon a stigma, they are not real seeds, 

 but only the representatives of those organs amongst Flowerless 

 plants. 



How simple is all this; how different from everything we 

 have seen in other plants — and yet no doubt as perfectly 

 adapted to the multiplication of Ferns as any more complete 

 contrivance. How prodigious too is the power that these plants 



