22 ' THE POLYPOD FERN. 



so end either in the edge (margin) of the frond, or in a 

 fruit-cluster (2). This kind of veining (venation) in the 

 larger veins is styled pinni-veined, or feather-veined, and 

 that in the veinulets -fork-veined. 



The Fruit is formed at the end of veinulets (1), on the 

 under surface (the back) of the frond.* It consists of 

 numerous round, reddish brown, regularly arranged patches 

 called sori (sorus, plur. sori, a heap). Under the microscope 

 these heaps (2) are found to be composed of numerous 

 roundish vessels (sporangia), each on a pedicel (3) and 

 filled with spores. The contrivance for opening these 

 spore cases is very curious. Each one is clasped by an 

 elastic, vertical ring. When ripe and dry, the ring con- 

 tracts, breaks asunder, tears open the cell (4), and throws 

 the spores (5) to a distance. f 



Classification. No flower is ever seen on this or any 

 other Fern.J Therefore they are classed with the Mosses 

 in the subkingdom CKYPTOGAMIA, or FLOWERLESS PLANTS. 



The Name. Polypod or Polypody is a contraction of 



* The spores of the brake are hidden under the margin of the leaves, so that 

 anciently it was thought that the Fern bears no seed. Later it was believed that the 

 fern-seed was visible only on St. John's Eve, just at the moment when the saint was 

 born : 



"But on St. John's mysterious night, 



Sacred to many a wizard spell, 

 The hour when first to human eight 



Confest, the mystic fern-seed fell." 



The superstitious belief that he who could at that hour get some of the fern-seed, 

 became invisible, is frequently alluded to by the old poets. Shakespeare says : 



" We have the receipt of fern-seed ; we walk invisible." 



+ The spores of the Ferns are numerous. Let the student calculate them in one of 

 these fronds. Professor Lindley observes of the Hart's-tongue (Scolopendrium), a 

 small Fern, that each frond produces about 80 fruit-clusters (sori), with an average of 

 about 4500 spore-cases in each cluster, and in each spore case 50 spores. The num- 

 ber of spores on each frond would then be 80 x 4500 x 50 = 18,000,000. If all should 

 grow, they would in a few years cover the whole continent. 



\ In germination, the spore of the Fern first develops into a green body resem- 

 bling a Liverwort, called the prothattus. On this prothallus are certain little organs 

 analogous to stamens and pistils, by which a second set of spores is generated, in 

 advance of the true Fern. Thus in the Fern, as in some insects, there is an alternate 

 generation; it is first a Liverwort, then a Fern. (See Zoology, p. 220, Aphidae.) 



